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US 7293855 B2 Zusammenfassung An inkjet drop ejection apparatus comprising:
If the ink supply channel is parallel with the direction of ink ejection, nozzle packing density on the printhead can be significantly increased. The ink can be supplied from the ‘back’ surface of the wafer, thereby removing the need for ink feed channels beside the chambers. This provides more room for the power and print data to be connected to each nozzle along the front surface of the wafer. Furthermore, ink supply channels leading directly to the nozzles promote a rapid ink refill rate under the action of the nozzle meniscus surface tension. Zeichnungen(565)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        Ansprüche 1. An inkjet drop ejection apparatus comprising: a chamber with a nozzle; an elongate ink inlet channel for fluid communication with an ink supply; and, an actuator with associated drive circuitry for ejecting drops of ink through the nozzle; wherein, the longitudinal axis of the ink inlet channel is substantially parallel to the trajectory of the ejected drops of ink. 2. 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An inkjet printhead comprising a substrate surface and an array of inkjet drop ejection apparatuses as claimed in 58. An inkjet printhead comprising a substrate surface and an array of inkjet drop ejection apparatuses as claimed in 59. An inkjet drop ejection apparatus as claimed in 60. An inkjet drop ejection apparatus as claimed in 61. An inkjet drop ejection apparatus as claimed in 62. An inkjet drop ejection apparatus as claimed in 63. An inkjet drop ejection apparatus as claimed in 64. An inkjet drop ejection apparatus as claimed in 65. An inkjet drop ejection apparatus as claimed in 66. An inkjet drop ejection apparatus as claimed in 67. An inkjet drop ejection apparatus as claimed in 68. An inkjet drop ejection apparatus as claimed in 69. An inkjet drop ejection apparatus as claimed in 70. An inkjet drop ejection apparatus as claimed in 71. An inkjet drop ejection apparatus as claimed in 72. An inkjet drop ejection apparatus as claimed in 73. 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An inkjet drop ejection apparatus as claimed in 112. An inkjet drop ejection apparatus as claimed in 113. An inkjet drop ejection apparatus as claimed in 114. An inkjet drop ejection apparatus as claimed in 115. An inkjet drop ejection apparatus as claimed in 116. An inkjet drop ejection apparatus as claimed in 117. An inkjet drop ejection apparatus as claimed in 118. An inkjet drop ejection apparatus as claimed in 119. An office printer comprising an inkjet drop ejection apparatus as claimed in 120. A short run digital printer comprising an inkjet drop ejection apparatus as claimed in 121. A high speed digital printer comprising an inkjet drop ejection apparatus as claimed in 122. A notebook computer incorporating a printer comprising an inkjet drop ejection apparatus as claimed in 123. An offset press supplemental printer comprising an inkjet drop ejection apparatus as claimed in 124. A pagewidth printer comprising an inkjet drop ejection apparatus as claimed in 125. A portable printer comprising an inkjet drop ejection apparatus as claimed in 126. A copier comprising an inkjet drop ejection apparatus as claimed in 127. A facsimile machine comprising an inkjet drop ejection apparatus as claimed in 128. A label printer comprising an inkjet drop ejection apparatus as claimed in 129. A large format printer comprising an inkjet drop ejection apparatus as claimed in 130. A photograph copier comprising an inkjet drop ejection apparatus as claimed in 131. A digital photographic minilab incorporating a printer comprising an inkjet drop ejection apparatus as claimed in 132. A video printer comprising an inkjet drop ejection apparatus as claimed in 133. A PDA incorporating a printer comprising an inkjet drop ejection apparatus as claimed in 134. A wallpaper printer comprising an inkjet drop ejection apparatus as claimed in 135. An indoor sign printer comprising an inkjet drop ejection apparatus as claimed in 136. A billboard printer comprising an inkjet drop ejection apparatus as claimed in 137. A fabric printer comprising an inkjet drop ejection apparatus as claimed in 138. A camera printer comprising an inkjet drop ejection apparatus as claimed in 139. A commercial printer array comprising an inkjet drop ejection apparatus as claimed in Beschreibung This is a CIP Application of U.S. application Ser. No. 10/407,212, filed on Apr. 7, 2003, which is a Continuation Application of U.S. application Ser. No. 09/113,122, filed on Jul. 10, 1998, now issued as U.S. Pat. No. 6,557,977, the entire contents of which are herein incorporated by reference. The following Australian provisional patent applications are hereby incorporated by reference. For the purposes of location and identification, US patents/patent applications identified by their US patent/patent application serial numbers are listed alongside the Australian applications from which the US patents/patent applications claim the right of priority.
Not applicable. The present invention relates to the operation and construction of an ink jet printer device. Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc. In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature. Many different techniques of ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, “Non-Impact Printing: Introduction and Historical Perspective”, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988). Ink Jet printers themselves come in many different forms. The utilization of a continuous stream of ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electrostatic ink jet printing. U.S. Pat. No. 3,596,275 by Sweet also discloses a process of continuous ink jet printing including a step wherein the ink jet stream is modulated by a high frequency electrostatic field so as to cause drop separation. This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al). Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element. Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques which rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices utilizing the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard. As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables. A compact design requires close nozzle spacing. One complication with high nozzle density on a printhead is the ink, power and print data supply to each and every nozzle. Accordingly, the invention provides an inkjet drop ejection apparatus comprising: a chamber with a nozzle; an elongate ink inlet channel for fluid communication with an ink supply; and, an actuator with associated drive circuitry for ejecting drops of ink through the nozzle; wherein, the longitudinal axis of the ink supply channel is substantially parallel to the trajectory of the ejected drops of ink. If the ink supply channel is parallel with the direction of ink ejection, nozzle packing density on the printhead can be significantly increased. The ink can be supplied from the ‘back’ surface of the wafer, thereby removing the need for ink feed channels beside the chambers. This provides more room for the power and print data to be connected to each nozzle along the front surface of the wafer. Furthermore, ink supply channels leading directly to the nozzles promote a rapid ink refill rate under the action of the nozzle meniscus surface tension. The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For a general introduction to micro-electric mechanical systems (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field. For color photographic applications, the print head is 100 mm long, with a width which depends upon the ink jet type. The smallest print head designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry. Tables of Drop-on-Demand Ink Jets Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee. The following tables form the axes of an eleven dimensional table of ink jet types.
The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. These are designated IJ01 to IJ46. Other ink jet configurations can readily be derived from these 46 examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ46 examples can be made into ink jet print heads with characteristics superior to any currently available ink jet technology. Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ46 series are also listed in the examples column. In some cases, a printer may be listed more than once in a table, where it shares characteristics with more than one entry. Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc. The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.
In The nozzle 104 operates on the principle of electromechanical energy conversion and comprises a solenoid 111 which is connected electrically at a first end 112 to a magnetic plate 113 which is in turn connected to a current source e.g. 114 utilized to activate the ink nozzle 104. The magnetic plate 113 can be constructed from electrically conductive iron. A second magnetic plunger 115 is also provided, again being constructed from soft magnetic iron. Upon energising the solenoid 111, the plunger 115 is attracted to the fixed magnetic plate 113. The plunger thereby pushes against the ink within the nozzle 104 creating a high pressure zone in the nozzle chamber 117. This causes a movement of the ink in the nozzle chamber 117 and in a first design, subsequent ejection of an ink drop. A series of apertures e.g. 120 is provided so that ink in the region of solenoid 111 is squirted out of the holes 120 in the top of the plunger 115 as it moves towards lower plate 113. This prevents ink trapped in the area of solenoid 111 from increasing the pressure on the plunger 115 and thereby increasing the magnetic forces needed to move the plunger 115. Referring now to Turning now to However, in a first design the plate 115 preferably includes a series of apertures e.g. 120 which allow for the flow of ink from the area 164 back into the ink chamber and thereby allow a reduction in the pressure in area 164. This results in an increased effectiveness in the operation of the plate 115. Preferably, the apertures 120 are of a teardrop shape increasing in width with increasing radial distance from a centre of the plunger. The aperture profile thereby provides minimal disturbance of the magnetic flux through the plunger while maintaining structural integrity of plunger 115. After the plunger 115 has reached its end position, the current through coil 111 is reversed resulting in a repulsion of the two plates 113, 115. Additionally, the torsional spring e.g. 123 acts to return the plate 115 to its initial position. The use of a torsional spring e.g. 123 has a number of substantial benefits including a compact layout. The construction of the torsional spring from the same material and same processing steps as that of the plate 115 simplifies the manufacturing process. In an alternative design, the top surface of plate 115 does not include a series of apertures. Rather, the inner radial surface 125 (see Fabrication Returning now to Next, a CMOS silicon layer 142 is provided upon which is fabricated all the data storage and driving circuitry 141 necessary for the operation of the nozzle 4. In this layer a nozzle chamber 117 is also constructed. The nozzle chamber 117 should be wide enough so that viscous drag from the chamber walls does not significantly increase the force required of the plunger. It should also be deep enough so that any air ingested through the nozzle port 124 when the plunger returns to its quiescent state does not extend to the plunger device. If it does, the ingested bubble may form a cylindrical surface instead of a hemispherical surface resulting in the nozzle not refilling properly. A CMOS dielectric and insulating layer 144 containing various current paths for the current connection to the plunger device is also provided. Next, a fixed plate of ferroelectric material is provided having two parts 113, 146. The two parts 113, 146 are electrically insulated from one another. Next, a solenoid 111 is provided. This can comprise a spiral coil of deposited copper. Preferably a single spiral layer is utilized to avoid fabrication difficulty and copper is used for a low resistivity and high electro-migration resistance. Next, a plunger 115 of ferromagnetic material is provided to maximise the magnetic force generated. The plunger 115 and fixed magnetic plate 113, 146 surround the solenoid 111 as a torus. Thus, little magnetic flux is lost and the flux is concentrated around the gap between the plunger 115 and the fixed plate 113, 146. The gap between the fixed plate 113, 146 and the plunger 115 is one of the most important “parts” of the print nozzle 104. The size of the gap will strongly affect the magnetic force generated, and also limits the travel of the plunger 115. A small gap is desirable to achieve a strong magnetic force, but a large gap is desirable to allow longer plunger 115 travel, and therefore allow a smaller plunger radius to be utilised. Next, the springs, e.g. 122, 123 for returning to the plunger 115 to its quiescent position after a drop has been ejected are provided. The springs, e.g. 122, 123 can be fabricated from the same material, and in the same processing steps, as the plunger 115. Preferably the springs, e.g. 122, 123 act as torsional springs in their interaction with the plunger 115. Finally, all surfaces are coated with passivation layers, which may be silicon nitride (Si3N4), diamond like carbon (DLC), or other chemically inert, highly impermeable layer. The passivation layers are especially important for device lifetime, as the active device will be immersed in the ink. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron 150. 2. Deposit 10 microns of epitaxial silicon 142, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown at 141 in 4. Etch the CMOS oxide layers 141 down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, the edges of the print heads chips, and the vias for the contacts from the aluminum electrodes to the two halves of the split fixed magnetic plate. 5. Plasma etch the silicon 142 down to the boron doped buried layer 150, using oxide from step 4 as a mask. This etch does not substantially etch the aluminum. This step is shown in 6. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)]. 7. Spin on 4 microns of resist 151, expose with Mask 2, and develop. This mask defines the split fixed magnetic plate, for which the resist acts as an electroplating mold. This step is shown in 8. Electroplate 3 microns of CoNiFe 152. This step is shown in 9. Strip the resist 151 and etch the exposed seed layer. This step is shown in 10. Deposit 0.1 microns of silicon nitride (Si3N4). 11. Etch the nitride layer using Mask 3. This mask defines the contact vias from each end of the solenoid coil to the two halves of the split fixed magnetic plate. 12. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 13. Spin on 5 microns of resist 153, expose with Mask 4, and develop. This mask defines the solenoid spiral coil and the spring posts, for which the resist acts as an electroplating mold. This step is shown in 14. Electroplate 4 microns of copper 154. 15. Strip the resist 153 and etch the exposed copper seed layer. This step is shown in 16. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 17. Deposit 0.1 microns of silicon nitride. 18. Deposit 1 micron of sacrificial material 156. This layer 156 determines the magnetic gap. 19. Etch the sacrificial material 156 using Mask 5. This mask defines the spring posts. This step is shown in 20. Deposit a seed layer of CoNiFe. 21. Spin on 4.5 microns of resist 157, expose with Mask 6, and develop. This mask defines the walls of the magnetic plunger, plus the spring posts. The resist forms an electroplating mold for these parts. This step is shown in 22. Electroplate 4 microns of CoNiFe 158. This step is shown in 23. Deposit a seed layer of CoNiFe. 24. Spin on 4 microns of resist 159, expose with Mask 7, and develop. This mask defines the roof of the magnetic plunger, the springs, and the spring posts. The resist forms an electroplating mold for these parts. This step is shown in 25. Electroplate 3 microns of CoNiFe 160. This step is shown in 26. Mount the wafer on a glass blank 161 and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer 150. This step is shown in 27. Plasma back-etch the boron doped silicon layer 150 to a depth of (approx.) 1 micron using Mask 8. This mask defines the nozzle rim 162. This step is shown in 28. Plasma back-etch through the boron doped layer using Mask 9. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 29. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in 30. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 31. Connect the print heads to their interconnect systems. 32. Hydrophobize the front surface of the printheads. 33. Fill the completed print heads with ink 163 and test them. A filled nozzle is shown in IJ02 In a preferred embodiment, an ink jet print head is made up of a plurality of nozzle chambers each having an ink ejection port. Ink is ejected from the ink ejection port through the utilization of attraction between two parallel plates. Turning initially to Ink is supplied to the nozzle chamber 211 via an ink supply channel, e.g. 215. Turning now to Next, an air gap 227 is provided between the top and bottom layers. This is followed by a further PTFE layer 228 which forms part of the top plate 222. The two PTFE layers 221, 228 are provided so as to reduce possible stiction effects between the upper and lower plates. Next, a top aluminum electrode layer 230 is provided followed by a nitride layer (not shown) which provides structural integrity to the top electro plate. The layers 228-230 are fabricated so as to include a corrugated portion 223 which concerts upon movement of the top plate 222. By placing a potential difference across the two aluminum layers 219 and 230, the top plate 222 is attracted to bottom aluminum layer 219 thereby resulting in a movement of the top plate 222 towards the bottom plate 219. This results in energy being stored in the concertinaed spring arrangement 223 in addition to air passing out of the side air holes, e.g. 233 and the ink being sucked into the nozzle chamber as a result of the distortion of the meniscus over the ink ejection port 212 ( The ink jet nozzles of a preferred embodiment can be formed from utilization of semi-conductor fabrication and MEMS techniques. Turning to Obviously, print heads can be formed from large arrays of nozzle arrangements 210 on a single wafer which is subsequently diced into separate print heads. Ink supply can be either from the side of the wafer or through the wafer utilizing deep anisotropic etching systems such as high density low pressure plasma etching systems available from surface technology systems. Further, the corrugated portion 223 can be formed through the utilisation of a half tone mask process. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 240, complete a 0.5 micron, one poly, 2 metal CMOS process 242. This step is shown in 2. Etch the passivation layers 246 to expose the bottom electrode 244, formed of second level metal. This etch is performed using Mask 1. This step is shown in 3. Deposit 50 nm of PTFE or other highly hydrophobic material. 4. Deposit 0.5 microns of sacrificial material, e.g. polyimide 248. 5. Deposit 0.5 microns of (sacrificial) photosensitive polyimide. 6. Expose and develop the photosensitive polyimide using Mask 2. This mask is a gray-scale mask which defines the concertina edge 250 of the upper electrode. The result of the etch is a series of triangular ridges at the circumference of the electrode. This concertina edge is used to convert tensile stress into bend strain, and thereby allow the upper electrode to move when a voltage is applied across the electrodes. This step is shown in 7. Etch the polyimide and passivation layers using Mask 3, which exposes the contacts for the upper electrode which are formed in second level metal. 8. Deposit 0.1 microns of tantalum 252, forming the upper electrode. 9. Deposit 0.5 microns of silicon nitride (Si3N4), which forms the movable membrane of the upper electrode. 10. Etch the nitride and tantalum using Mask 4. This mask defines the upper electrode, as well as the contacts to the upper electrode. This step is shown in 11. Deposit 12 microns of (sacrificial) photosensitive polyimide 254. 12. Expose and develop the photosensitive polyimide using Mask 5. A proximity aligner can be used to obtain a large depth of focus, as the line-width for this step is greater than 2 microns, and can be 5 microns or more. This mask defines the nozzle chamber walls. This step is shown in 13. Deposit 3 microns of PECVD glass 256. This step is shown in 14. Etch to a depth of 1 micron using Mask 6. This mask defines the nozzle rim 258. This step is shown in 15. Etch down to the sacrificial layer 254 using Mask 7. This mask defines the roof of the nozzle chamber, and the nozzle 260 itself. This step is shown in 16. Back-etch completely through the silicon wafer 246 (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 8. This mask defines the ink inlets 262 which are etched through the wafer 240. The wafer 240 is also diced by this etch. 17. Back-etch through the CMOS oxide layer through the holes in the wafer 240. This step is shown in 18. Etch the sacrificial polyimide 254. The nozzle chambers 264 are cleared, a gap is formed between the electrodes and the chips are separated by this etch. To avoid stiction, a final rinse using supercooled carbon dioxide can be used. This step is shown in 19. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. 20. Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 21. Hydrophobize the front surface of the print heads. 22. Fill the completed print heads with ink 266 and test them. A filled nozzle is shown in IJ03 In a preferred embodiment, there is provided an ink jet printer having nozzle chambers. Each nozzle chamber includes a thermoelastic bend actuator that utilizes a planar resistive material in the construction of the bend actuator. The bend actuator is activated when it is required to eject ink from a chamber. Turning now to The nozzle arrangement 310 includes a nozzle chamber 316 which can be constructed by utilization of an anisotropic crystallographic etch of the silicon portions 318 of the wafer. On top of the silicon portions 318 is included a glass layer 320 which can comprise CMOS drive circuitry including a two level metal layer (not shown) so as to provide control and drive circuitry for the thermal actuator. On top of the CMOS glass layer 320 is provided a nitride layer 321 which includes side portions 322 which act to passivate lower layers from etching that is utilized in construction of the nozzle arrangement 310. The nozzle arrangement 310 includes a paddle actuator 324 which is constructed on a nitride base 325 which acts to form a rigid paddle for the overall actuator 324. Next, an aluminum layer 327 is provided with the aluminum layer 327 being interconnected by vias 328 with the lower CMOS circuitry so as to form a first portion of a circuit. The aluminum layer 327 is interconnected at a point 330 to an Indium Tin Oxide (ITO) layer 329 which provides for resistive heating on demand. The ITO layer 329 includes a number of etch holes 331 for allowing the etching away of a lower level sacrificial layer which is formed between the layers 327, 329. The ITO layer is further connected to the lower glass CMOS circuitry layer by via 332. On top of the ITO layer 329 is optionally provided a polytetrafluoroethylene layer (not shown) which provides for insulation and further rapid expansion of the top layer 329 upon heating as a result of passing a current through the bottom layer 327 and ITO layer 329. The back surface of the nozzle arrangement 310 is placed in an ink reservoir so as to allow ink to flow into nozzle chamber 316. When it is desired to eject a drop of ink, a current is passed through the aluminum layer 327 and ITO layer 329. The aluminum layer 327 provides a very low resistance path to the current whereas the ITO layer 329 provides a high resistance path to the current. Each of the layers 327, 329 are passivated by means of coating by a thin nitride layer (not shown) so as to insulate and passivate the layers from the surrounding ink. Upon heating of the ITO layer 329 and optionally PTFE layer, the top of the actuator 324 expands more rapidly than the bottom portions of the actuator 324. This results in a rapid bending of the actuator 324, particularly around the point 335 due to the utilization of the rigid nitride paddle arrangement 325. This accentuates the downward movement of the actuator 324 which results in the ejection of ink from ink ejection nozzle 313. Between the two layers 327, 329 is provided a gap 360 which can be constructed via utilization of etching of sacrificial layers so as to dissolve away sacrificial material between the two layers. Hence, in operation ink is allowed to enter this area and thereby provides a further cooling of the lower surface of the actuator 324 so as to assist in accentuating the bending. Upon de-activation of the actuator 324, it returns to its quiescent position above the nozzle chamber 316. The nozzle chamber 316 refills due to the surface tension of the ink through the gaps between the actuator 324 and the nozzle chamber 316. The PTFE layer has a high coefficient of thermal expansion and therefore further assists in accentuating any bending of the actuator 324. Therefore, in order to eject ink from the nozzle chamber 316, a current is passed through the planar layers 327, 329 resulting in resistive heating of the top layer 329 which further results in a general bending down of the actuator 324 resulting in the ejection of ink. The nozzle arrangement 310 is mounted on a second silicon chip wafer which defines an ink reservoir channel to the back of the nozzle arrangement 310 for resupply of ink. Turning now to One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron 312. 2. Deposit 10 microns of epitaxial silicon 318, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process 320. This step is shown in 4. Etch the CMOS oxide layers down to silicon 318 or second level metal using Mask 1. This mask defines the nozzle cavity and the bend actuator electrode contact vias 328, 332. This step is shown in 5. Crystallographically etch the exposed silicon 318 using KOH as shown at 340. This etch stops on <111> crystallographic planes 361, and on the boron doped silicon buried layer 312. This step is shown in 6. Deposit 0.5 microns of low stress PECVD silicon nitride 341 (Si3N4). The nitride 341 acts as an ion diffusion barrier. This step is shown in 7. Deposit a thick sacrificial layer 342 (e.g. low stress glass), filling the nozzle cavity. Planarize the sacrificial layer 342 down to the nitride 341 surface. This step is shown in 8. Deposit 1 micron of tantalum 343. This layer acts as a stiffener for the bend actuator. 9. Etch the tantalum 343 using Mask 2. This step is shown in 10. Etch nitride 341 still using Mask 2. This clears the nitride from the electrode contact vias 328, 332. This step is shown in 11. Deposit one micron of gold 344, patterned using Mask 3. This may be deposited in a lift-off process. Gold is used for its corrosion resistance and low Young's modulus. This mask defines the lower conductor of the bend actuator. This step is shown in 12. Deposit 1 micron of thermal blanket 345. This material should be a non-conductive material with a very low Young's modulus and a low thermal conductivity, such as an elastomer or foamed polymer. 13. Pattern the thermal blanket 345 using Mask 4. This mask defines the contacts between the upper and lower conductors, and the upper conductor and the drive circuitry. This step is shown in 14. Deposit 1 micron of a material 346 with a very high resistivity (but still conductive), a high Young's modulus, a low heat capacity, and a high coefficient of thermal expansion. A material such as indium tin oxide (ITO) may be used, depending upon the dimensions of the bend actuator. 15. Pattern the ITO 346 using Mask 5. This mask defines the upper conductor of the bend actuator. This step is shown in 16. Deposit a further 1 micron of thermal blanket 347. 17. Pattern the thermal blanket 347 using Mask 6. This mask defines the bend actuator, and allows ink to flow around the actuator into the nozzle cavity. This step is shown in 18. Mount the wafer on a glass blank 348 and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer 312. This step is shown in 19. Plasma back-etch the boron doped silicon layer 312 to a depth of 1 micron using Mask 7. This mask defines the nozzle rim 314. This step is shown in 20. Plasma back-etch through the boron doped layer 312 using Mask 8. This mask defines the nozzle 313, and the edge of the chips. 21. Plasma back-etch nitride 341 up to the glass sacrificial layer 342 through the holes in the boron doped silicon layer 312. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 22. Strip the adhesive layer to detach the chips from the glass blank 348. 23. Etch the sacrificial glass layer 342 in buffered HF. This step is shown in 24. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 25. Connect the printheads to their interconnect systems. 26. Hydrophobize the front surface of the printheads. 27. Fill the completed printheads with ink 350 and test them. A filled nozzle is shown in IJ04 In a preferred embodiment, a stacked capacitive actuator is provided which has alternative electrode layers sandwiched between a compressible polymer. Hence, on activation of the stacked capacitor the plates are drawn together compressing the polymer thereby storing energy in the compressed polymer. The capacitor is then de-activated or drained with the result that the compressed polymer acts to return the actuator to its original position and thereby causes the ejection of ink from an ink ejection port. Turning now to After sufficient time, the meniscus 414 returns to its quiescent position with the capacitor 413 being loaded ready for firing ( Turning now to In alternative designs, the stacked capacitor device 413 consists of other thin film materials in place of the styrene-ethylene-butylene-styrene block copolymer. Such materials may include: 1) Piezoelectric materials such as PZT 2) Electrostrictive materials such as PLZT 3) Materials, that can be electrically switched between a ferro-electric and an anti-ferro-electric phase such as PLZSnT. Importantly, the electrode actuator 413 can be rapidly constructed utilizing chemical vapor deposition (CVD) techniques. The various layers, 420, 421, 422 can be laid down on a planar wafer one after another covering the whole surface of the wafer. A stack can be built up rapidly utilizing CVD techniques. The two sets of electrodes are preferably deposited utilizing separate metals. For example, aluminum and tantalum could be utilized as materials for the metal layers. The utilization of different metal layers allows for selective etching utilizing a mask layer so as to form the structure as indicated in Construction of the Ink Nozzle Arrangement Turning now to One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 430, complete a 0.5 micron, one poly, 2 metal CMOS layer 431 process. This step is shown in 2. Etch the CMOS oxide layers 431 to second level metal using Mask 1. This mask defines the contact vias from the electrostatic stack to the drive circuitry. 3. Deposit 0.1 microns of aluminum. 4. Deposit 0.1 microns of elastomer. 5. Deposit 0.1 microns of tantalum. 6. Deposit 0.1 microns of elastomer. 7. Repeat steps 2 to 5 twenty times to create a stack 440 of alternating metal and elastomer which is 8 microns high, with 40 metal layers and 40 elastomer layers. This step is shown in 8. Etch the stack 440 using Mask 2. This leaves a separate rectangular multi-layer stack 413 for each nozzle. This step is shown in 9. Spin on resist 441, expose with Mask 3, and develop. This mask defines one side of the stack 413. This step is shown in 10. Etch the exposed elastomer layers to a horizontal depth of 1 micron. 11. Wet etch the exposed aluminum layers to a horizontal depth of 3 microns. 12. Foam the exposed elastomer layers by 50 nm to close the 0.1 micron gap left by the etched aluminum. 13. Strip the resist 441. This step is shown in 14. Spin on resist 442, expose with Mask 4, and develop. This mask defines the opposite side of the stack 413. This step is shown in 15. Etch the exposed elastomer layers to a horizontal depth of 1 micron. 16. Wet etch the exposed tantalum layers to a horizontal depth of 3 microns. 17. Foam the exposed elastomer layers by 50 nm to close the 0.1 micron gap left by the etched aluminum. 18. Strip the resist 442. This step is shown in 19. Deposit 1.5 microns of tantalum 443. This metal contacts all of the aluminum layers on one side of the stack 413, and all of the tantalum layers on the other side of the stack 413. 20. Etch the tantalum 443 using Mask 5. This mask defines the electrodes at both edges of the stack 413. This step is shown in 21. Deposit 18 microns of sacrificial material 444 (e.g. photosensitive polyimide). 22. Expose and develop the sacrificial layer 444 using Mask 6 using a proximity aligner. This mask defines the nozzle chamber walls 434 and inlet filter. This step is shown in 23. Deposit 3 microns of PECVD glass 445. 24. Etch to a depth of 1 micron using Mask 7. This mask defines the nozzle rim 450. This step is shown in 25. Etch down to the sacrificial layer 444 using Mask 8. This mask defines the roof 437 of the nozzle chamber, and the nozzle 411 itself. This step is shown in 26. Back-etch completely through the silicon wafer 430 (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 9. This mask defines the ink inlets 447 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in 27. Back-etch through the CMOS oxide layer 431 through the holes in the wafer. 28. Etch the sacrificial material 444. The nozzle chambers 412 are cleared, and the chips are separated by this etch. This step is shown in 29. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. 30. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 31. Hydrophobize the front surface of the printheads. 32. Fill the completed printheads with ink 448 and test them. A filled nozzle is shown in IJ05 A preferred embodiment of the present invention relies upon a magnetic actuator to “load” a spring, such that, upon deactivation of the magnetic actuator the resultant movement of the spring causes ejection of a drop of ink as the spring returns to its original position. Turning to The operation of the ink nozzle arrangement 501 of The moveable soft magnetic pole is balanced by a fulcrum 508 with a piston head 509. Movement of the magnetic pole 505 closer to the stationary pole 504 causes the piston head 509 to move away from a nozzle chamber 511 drawing air into the chamber 511 via an ink ejection port 513. The piston 509 is then held open above the nozzle chamber 511 by means of maintaining a low “keeper” current through solenoid 502. The keeper level current through solenoid 502 being sufficient to maintain the moveable pole 505 against the fixed soft magnetic pole 504. The level of current will be substantially less than the maximum current level because the gap between the two poles 504 and 505 is at a minimum. For example, a keeper level current of 10% of the maximum current level may be suitable. During this phase of operation, the meniscus of ink at the nozzle tip or ink ejection port 513 is a concave hemisphere due to the in flow of air. The surface tension on the meniscus exerts a net force on the ink which results in ink flow from the ink chamber into the nozzle chamber 511. This results in the nozzle chamber refilling, replacing the volume taken up by the piston head 509 which has been withdrawn. This process takes approximately 100 microseconds. The current within solenoid 502 is then reversed to half that of the maximum current. The reversal demagnetises the magnetic poles and initiates a return of the piston 509 to its rest position. The piston 509 is moved to its normal rest position by both the magnetic repulsion and by the energy stored in a stressed tortional spring 516, 519 which was put in a state of torsion upon the movement of moveable pole 505. The forces applied to the piston 509 as a result of the reverse current and spring 516, 519 will be greatest at the beginning of the movement of the piston 509 and will decrease as the spring elastic stress falls to zero. As a result, the acceleration of piston 509 is high at the beginning of a reverse stroke and the resultant ink velocity within the chamber 511 becomes uniform during the stroke. This results in an increased operating tolerance before ink flow over the printhead surface will occur. At a predetermined time during the return stroke, the solenoid reverse current is turned off. The current is turned off when the residual magnetism of the movable pole is at a minimum. The piston 509 continues to move towards its original rest position. The piston 509 will overshoot the quiescent or rest position due to its inertia. Overshoot in the piston movement achieves two things: greater ejected drop volume and velocity, and improved drop break off as the piston returns from overshoot to its quiescent position. The piston 509 will eventually return from overshoot to the quiescent position. This return is caused by the springs 516, 519 which are now stressed in the opposite direction. The piston return “sucks” some of the ink back into the nozzle chamber 511, causing the ink ligament connecting the ink drop to the ink in the nozzle chamber 511 to thin. The forward velocity of the drop and the backward velocity of the ink in the nozzle chamber 511 are resolved by the ink drop breaking off from the ink in the nozzle chamber 511. The piston 509 stays in the quiescent position until the next drop ejection cycle. A liquid ink printhead has one ink nozzle arrangement 501 associated with each of the multitude of nozzles. The arrangement 501 has the following major parts: (1) Drive circuitry 503 for driving the solenoid 502. (2) An ejection port 513. The radius of the ejection port 513 is an important determinant of drop velocity and drop size. (3) A piston 509. This is a cylinder which moves through the nozzle chamber 511 to expel the ink. The piston 509 is connected to one end of the lever arm 517. The piston radius is approximately 1.5 to 2 times the radius of the ejection port 513. The ink drop volume output is mostly determined by the volume of ink displaced by the piston 509 during the piston return stroke. (4) A nozzle chamber 511. The nozzle chamber 511 is slightly wider than the piston 509. The gap between the piston 509 and the nozzle chamber walls is as small as is required to ensure that the piston does not contact the nozzle chamber during actuation or return. If the printheads are fabricated using 0.5 micron semiconductor lithography, then a 1 micron gap will usually be sufficient. The nozzle chamber is also deep enough so that air ingested through the ejection port 513 when the plunger 509 returns to its quiescent state does not extend to the piston 509. If it does, the ingested bubble may form a cylindrical surface instead of a hemispherical surface. If this happens, the nozzle will not refill properly. (5) A solenoid 502. This is a spiral coil of copper. Copper is used for its low resistivity, and high electro-migration resistance. (6) A fixed magnetic pole of ferromagnetic material 504. (7) A moveable magnetic pole of ferromagnetic material 505. To maximise the magnetic force generated, the moveable magnetic pole 505 and fixed magnetic pole 504 surround the solenoid 502 as a torus. Thus little magnetic flux is lost, and the flux is concentrated across the gap between the moveable magnetic pole 505 and the fixed pole 504. The moveable magnetic pole 505 has holes in the surface 506 ( (8) A magnetic gap. The gap between the fixed plate 504 and the moveable magnetic pole 505 is one of the most important “parts” of the print actuator. The size of the gap strongly affects the magnetic force generated, and also limits the travel of the moveable magnetic pole 505. A small gap is desirable to achieve a strong magnetic force. The travel of the piston 509 is related to the travel of the moveable magnetic pole 505 (and therefore the gap) by the lever arm 517. (9) Length of the lever arm 517. The lever arm 517 allows the travel of the piston 509 and the moveable magnetic pole 505 to be independently optimised. At the short end of the lever arm 517 is the moveable magnetic pole 505. At the long end of the lever arm 517 is the piston 509. The spring 516 is at the fulcrum 508. The optimum travel for the moveable magnetic pole 505 is less than 1 micron, so as to minimise the magnetic gap. The optimum travel for the piston 509 is approximately 5 micron for a 1200 dpi printer. The difference in optimum travel is resolved by a lever 517 with a 5:1 or greater ratio in arm length. (10) Springs 516, 519 ( (11) Passivation layers (not shown). All surfaces are preferably coated with passivation layers, which may be silicon nitride (Si3N4), diamond like carbon (DLC), or other chemically inert, highly impermeable layer. The passivation layers are especially important for device lifetime, as the active device is immersed in the ink. As will be evident from the foregoing description there is an advantage in ejecting the drop on deactivation of the solenoid 502. This advantage comes from the rate of acceleration of the moving magnetic pole 505 which is used as a piston or plunger. The force produced by a moveable magnetic pole by an electromagnetic induced field is approximately proportional to the inverse square of the gap between the moveable 505 and static magnetic poles 504. When the solenoid 502 is off, this gap is at a maximum. When the solenoid 502 is turned on, the moving pole 505 is attracted to the static pole 504. As the gap decreases, the force increases, accelerating the movable pole 505 faster. The velocity increases in a highly non-linear fashion, approximately with the square of time. During the reverse movement of the moving pole 505 upon deactivation the acceleration of the moving pole 505 is greatest at the beginning and then slows as the spring elastic stress falls to zero. As a result, the velocity of the moving pole 505 is more uniform during the reverse stroke movement. (1) The velocity of piston or plunger 509 is much more constant over the duration of the drop ejection stroke. (2) The piston or plunger 509 can readily be entirely removed from the ink chamber during the ink fill stage, and thereby the nozzle filling time can be reduced, allowing faster printhead operation. However, this approach does have some disadvantages over a direct firing type of actuator: (1) The stresses on the spring 516 are relatively large. Careful design is required to ensure that the springs operate at below the yield strength of the materials used. (2) The solenoid 502 must be provided with a “keeper” current for the nozzle fill duration. The keeper current will typically be less than 10% of the solenoid actuation current However, the nozzle fill duration is typically around 50 times the drop firing duration, so the keeper energy will typically exceed the solenoid actuation energy. (3) The operation of the actuator is more complex due to the requirement for a “keeper” phase. The printhead is fabricated from two silicon wafers. A first wafer is used to fabricate the print nozzles (the printhead wafer) and a second wafer (the Ink Channel Wafer) is utilized to fabricate the various ink channels in addition to providing a support means for the first channel. The fabrication process then proceeds as follows: (1) Start with a single crystal silicon wafer 520, which has a buried epitaxial layer 522 of silicon which is heavily doped with boron. The boron should be doped to preferably 1020 atoms per cm3 of boron or more, and be approximately 3 micron thick, and be doped in a manner suitable for the active semiconductor device technology chosen. The wafer diameter of the printhead wafer should be the same as the ink channel wafer. (2) Fabricate the drive transistors and data distribution circuitry 503 according to the process chosen (eg. CMOS). (3) Planarise the wafer 520 using chemical Mechanical Planarisation (CMP). (4) Deposit 5 micron of glass (SiO2) over the second level metal. (5) Using a dual damascene process, etch two levels into the top oxide layer. Level 1 is 4 micron deep, and level 2 is 5 micron deep. Level 2 contacts the second level metal. The masks for the static magnetic pole are used. (6) Deposit 5 micron of nickel iron alloy (NiFe). (7) Planarise the wafer using CMP, until the level of the SiO2 is reached forming the magnetic pole 504. (8) Deposit 0.1 micron of silicon nitride (Si3N4). (9) Etch the Si3N4 for via holes for the connections to the solenoids, and for the nozzle chamber region 511. (10) Deposit 4 micron of SiO2. (11) Plasma etch the SiO2 in using the solenoid and support post mask. (12) Deposit a thin diffusion barrier, such as Ti, TiN, or TiW, and an adhesion layer if the diffusion layer chosen has insufficient adhesion. (13) Deposit 4 micron of copper for forming the solenoid 502 and spring posts 524. The deposition may be by sputtering, CVD, or electroless plating. As well as lower resistivity than aluminium, copper has significantly higher resistance to electro-migration. The electro-migration resistance is significant, as current densities in the order of 3×106 Amps/cm2 may be required. Copper films deposited by low energy kinetic ion bias sputtering have been found to have 1,000 to 100,000 times larger electro-migration lifetimes larger than aluminum silicon alloy. The deposited copper should be alloyed and layered for maximum electro-migration lifetimes than aluminum silicon alloy. The deposited copper should be alloyed and layered for maximum electro-migration resistance, while maintaining high electrical conductivity. (14) Planarise the wafer using CMP, until the level of the SiO2 is reached. A damascene process is used for the copper layer due to the difficulty involved in etching copper. However, since the damascene dielectric layer is subsequently removed, processing is actually simpler if a standard deposit/etch cycle is used instead of damascene. However, it should be noted that the aspect ratio of the copper etch would be 8:1 for this design, compared to only 4:1 for a damascene oxide etch This difference occurs because the copper is 1 micron wide and 4 micron thick, but has only 0.5 micron spacing. Damascene processing also reduces the lithographic difficultly, as the resist is on oxide, not metal. (15) Plasma etch the nozzle chamber 511, stopping at the boron doped epitaxial silicon layer 521. This etch will be through around 13 micron of SiO2, and 8 micron of silicon. The etch should be highly anisotropic, with near vertical sidewalls. The etch stop detection can be on boron in the exhaust gasses. If this etch is selective against NiFe, the masks for this step and the following step can be combined, and the following step can be eliminated. This step also etches the edge of the printhead wafer down to the boron layer, for later separation. (16) Etch the SiO2 layer. This need only be removed in the regions above the NiFe fixed magnetic poles, so it can be removed in the previous step if an Si and SiO2 etch selective against NiFe is used. (17) Conformably deposit 0.5 micron of high density Si3N4. This forms a corrosion barrier, so should be free of pin-holes, and be impermeable to OH ions. (18) Deposit a thick sacrificial layer 540. This layer should entirely fill the nozzle chambers, and coat the entire wafer to an added thickness of 8 microns. The sacrificial layer may be SiO2. (19) Etch two depths in the sacrificial layer for a dual damascene process. The deep etch is 8 microns, and the shallow etch is 3 microns. The masks defines the piston 509, the lever arm 517, the springs 516 and the moveable magnetic pole 505. (20) Conformably deposit 0.1 micron of high density Si3N4. This forms a corrosion barrier, so should be free of pin-holes, and be impermeable to OH ions. (21) Deposit 8 micron of nickel iron alloy (NiFe). (22) Planarise the wafer using CMP, until the level of the SiO2 is reached. (23) Deposit 0.1 micron of silicon nitride (Si3N4). (24) Etch the Si3N4 everywhere except the top of the plungers. (25) Open the bond pads. (26) Permanently bond the wafer onto a pre-fabricated ink channel wafer. The active side of the printhead wafer faces the ink channel wafer. The ink channel wafer is attached to a backing plate, as it has already been etched into separate ink channel chips. (27) Etch the printhead wafer to entirely remove the backside silicon to the level of the boron doped epitaxial layer 522. This etch can be a batch wet etch in ethylenediamine pyrocatechol (EDP). (28) Mask the nozzle rim 514 from the underside of the printhead wafer. This mask also includes the chip edges. (31) Etch through the boron doped silicon layer 522, thereby creating the nozzle holes. This etch should also etch fairly deeply into the sacrificial material in the nozzle chambers to reduce time required to remove the sacrificial layer. (32) Completely etch the sacrificial material. If this material is SiO2 then a HF etch can be used. The nitride coating on the various layers protects the other glass dielectric layers and other materials in the device from HF etching. Access of the HF to the sacrificial layer material is through the nozzle, and simultaneously through the ink channel chip. The effective depth of the etch is 21 microns. (33) Separate the chips from the backing plate. Each chip is now a full printhead including ink channels. The two wafers have already been etched through, so the printheads do not need to be diced. (34) Test the printheads and TAB bond the good printheads. (35) Hydrophobize the front surface of the printheads. (36) Perform final testing on the TAB bonded printheads. One alternative form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron. 2. Deposit 10 microns of epitaxial silicon, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in 4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, the edges of the printheads chips, and the vias for the contacts from the aluminum electrodes to the two halves of the split fixed magnetic plate. 5. Plasma etch the silicon down to the boron doped buried layer, using oxide from step 4 as a mask. This etch does not substantially etch the aluminum. This step is shown in 6. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)]. 7. Spin on 4 microns of resist, expose with Mask 2, and develop. This mask defines the split fixed magnetic plate and the nozzle chamber wall, for which the resist acts as an electroplating mold. This step is shown in 8. Electroplate 3 microns of CoNiFe. This step is shown in 9. Strip the resist and etch the exposed seed layer. This step is shown in 10. Deposit 0.1 microns of silicon nitride (Si3N4). 11. Etch the nitride layer using Mask 3. This mask defines the contact vias from each end of the solenoid coil to the two halves of the split fixed magnetic plate. 12. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 13. Spin on 5 microns of resist, expose with Mask 4, and develop. This mask defines the solenoid spiral coil, the nozzle chamber wall and the spring posts, for which the resist acts as an electroplating mold. This step is shown in 14. Electroplate 4 microns of copper. 15. Strip the resist and etch the exposed copper seed layer. This step is shown in 16. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 17. Deposit 0.1 microns of silicon nitride. 18. Deposit 1 micron of sacrificial material. This layer determines the magnetic gap. 19. Etch the sacrificial material using Mask 5. This mask defines the spring posts and the nozzle chamber wall. This step is shown in 20. Deposit a seed layer of CoNiFe. 21. Spin on 4.5 microns of resist, expose with Mask 6, and develop. This mask defines the walls of the magnetic plunger, the lever arm, the nozzle chamber wall and the spring posts. The resist forms an electroplating mold for these parts. This step is shown in 22. Electroplate 4 microns of CoNiFe. This step is shown in 23. Deposit a seed layer of CoNiFe. 24. Spin on 4 microns of resist, expose with Mask 7, and develop. This mask defines the roof of the magnetic plunger, the nozzle chamber wall, the lever arm, the springs, and the spring posts. The resist forms an electroplating mold for these parts. This step is shown in 25. Electroplate 3 microns of CoNiFe. This step is shown in 26. Mount the wafer on a glass blank and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in 27. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 8. This mask defines the nozzle rim. This step is shown in 28. Plasma back-etch through the boron doped layer using Mask 9. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 29. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in 30. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 31. Connect the printheads to their interconnect systems. 32. Hydrophobize the front surface of the printheads. 33. Fill the completed printheads with ink and test them. A filled nozzle is shown in IJ06 Referring now to As can be seen from the cross section of The nozzle chamber 613 refills due to the surface tension of the ink at the ejection nozzle 611 after the ejection of ink. Manufacturing Construction Process The construction of the inkjet nozzles can proceed by way of utilisation of microelectronic fabrication techniques commonly known to those skilled in the field of semi-conductor fabrication. In accordance with one form of construction, two wafers are utilized upon which the active circuitry and ink jet print nozzles are fabricated and a further wafer in which the ink channels are fabricated. Turning now to Next, the drive transistors and distribution circuitry are constructed in accordance with the fabrication process chosen resulting in a CMOS logic and drive transistor level 643. A silicon nitride layer (not shown) is then deposited. The paddle metal layers are constructed utilizing a damascene process which is a well known process utilizing chemical mechanical polishing techniques (CMP) well known for utilization as a multi-level metal application. The solenoid coils in paddle 615 ( Next, a second layer 646 is deposited utilizing this time a dual damascene process. The copper layers 645, 646 include contact posts 647, 648, for interconnection of the electromagnetic coil to the CMOS layer 643 through vias in the silicon nitride layer (not shown). However, the metal post portion also includes a via interconnecting it with the lower copper level. The damascene process is finished with a planarized glass layer. The glass layers produced during utilisation of the damascene processes utilized for the deposition of layers 645, 646, are shown as one layer 675 in Subsequently, the paddle is formed and separated from the adjacent glass layer by means of a plasma etch as the etch being down to the position of silicon layer 642. Further, the nozzle chamber 613 underneath the panel is removed by means of a silicon anisotropic wet etch which will edge down to the boron layer 641. A passivation layer is then applied. The passivation layer can comprise a conformable diamond like carbon layer or a high density Si3N4 coating, this coating provides a protective layer for the paddle and its surrounds as the paddle must exist in the highly corrosive environment water and ink. Next, the silicon wafer can be back-etched through the boron doped layer and the ejection port 611 and an ejection port rim 650 ( One form of alternative detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 640 deposit 3 microns of epitaxial silicon heavily doped with boron 641. 2. Deposit 10 microns of epitaxial silicon 642, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process to form layers 643. This step is shown in 4. Deposit 0.1 microns of silicon nitride (Si3N4) (not shown). 5. Etch the nitride layer using Mask 1. This mask defines the contact vias from the solenoid coil to the second-level metal contacts. 6. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 7. Spin on 3 microns of resist 690, expose with Mask 2, and develop. This mask defines the first level coil of the solenoid. The resist acts as an electroplating mold. This step is shown in 8. Electroplate 2 microns of copper 645. 9. Strip the resist and etch the exposed copper seed layer. This step is shown in 10. Deposit 0.1 microns of silicon nitride (Si3N4) 691. 11. Etch the nitride layer using Mask 3. This mask defines the contact vias 647, 648 between the first level and the second level of the solenoid. 12. Deposit a seed layer of copper. 13. Spin on 3 microns of resist 692, expose with Mask 4, and develop. This mask defines the second level coil of the solenoid. The resist acts as an electroplating mold. This step is shown in 14. Electroplate 2 microns of copper 646. 15. Strip the resist and etch the exposed copper seed layer. This step is shown in 16. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 17. Deposit 0.1 microns of silicon nitride 693. 18. Etch the nitride and CMOS oxide layers down to silicon using Mask 5. This mask defines the nozzle chamber mask and the edges 670 of the print heads chips for crystallographic wet etching. This step is shown in FIG. 107. 19. Crystallographically etch the exposed silicon using KOH. This etch stops on <111> crystallographic planes 694, and on the boron doped silicon buried layer. Due to the design of Mask 5, this etch undercuts the silicon, providing clearance for the paddle to rotate downwards. 20. Mount the wafer on a glass blank 695 and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in 21. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 6. This mask defines the nozzle rim 650. This step is shown in 22. Plasma back-etch through the boron doped layer using Mask 7. This mask defines the ink ejection nozzle 611, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 23. Strip the adhesive layer to detach the chips from the glass blank. This step is shown in 24. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 25. Connect the print heads to their interconnect systems. 26. Hydrophobize the front surface of the print heads. 27. Fill with ink 696, apply a strong magnetic field in the plane of the chip surface, and test the completed print heads. A filled nozzle is shown in IJ07 Turning initially to Each nozzle apparatus 701 includes a nozzle outlet port 702 for the ejection of ink from a nozzle chamber 704 as a result of activation of an electromagnetic piston 705. The electromagnetic piston 705 is activated via a solenoid coil 706 which is positioned about the piston 705. When a current passes through the solenoid coil 706, the piston 705 experiences a force in the direction as indicated by an arrow 713. As a result, the piston 705 begins moving towards the outlet port 702 and thus imparts momentum to ink within the nozzle chamber 704. The piston 705 is mounted on torsional springs 708, 709 so that the springs 708, 709 act against the movement of the piston 705. The torsional springs 708 are configured so that they do not fully stop the movement of the piston 705. Upon completion of an ejection cycle, the current to the coil 706 is turned off. As a result, the torsional springs 708, 709 act to return the piston 705 to its rest position as initially shown in Current to the coil 706 is provided via aluminum connectors (not shown) which interconnect the coil 706 with a semi-conductor drive transistor and logic layer 718. Construction A liquid ink jet print head has one nozzle apparatus 701 associated with a respective one of each of a multitude of nozzle apparatus 701. It will be evident that each nozzle apparatus 701 has the following major parts, which are constructed using standard semi-conductor and micromechanical construction techniques: 1. Drive circuitry within the logic layer 718. 2. The nozzle outlet port 702. The radius of the nozzle outlet port 702 is an important determinant of drop velocity and drop size. 3. The magnetic piston 705. This can be manufactured from a rare earth magnetic material such as neodymium iron boron (NdFeB) or samarium cobalt (SaCo). The pistons 705 are magnetised after a last high temperature step in the fabrication of the print heads, to ensure that the Curie temperature is not exceeded after magnetisation. A typical print head may include many thousands of pistons 705 all of which can be magnetised simultaneously and in the same direction. 4. The nozzle chamber 704. The nozzle chamber 704 is slightly wider than the piston 705. The gap 750 between the piston 705 and the nozzle chamber 704 can be as small as is required to ensure that the piston 705 does not contact the nozzle chamber 704 during actuation or return of the piston 705. If the print heads are fabricated using a standard 0.5 μm lithography process, then a 1 μm gap will usually be sufficient. The nozzle chamber 704 should also be deep enough so that air ingested through the outlet port 702 when the piston 705 returns to its quiescent state does not extend to the piston 705. If it does, the ingested air bubble may form a cylindrical surface instead of a hemispherical surface. If this happens, the nozzle chamber 704 may not refill properly. 5. The solenoid coil 706. This is a spiral coil of copper. A double layer spiral is used to obtain a high field strength with a small device radius. Copper is used for its low resistivity, and high electro-migration resistance. 6. Springs 708. The springs 708 return the piston 705 to its quiescent position after a drop of ink has been ejected. The springs 708 can be fabricated from silicon nitride. 7. Passivation layers. All surfaces are coated with passivation layers, which may be silicon nitride (Si3N4), diamond like carbon (DLC), or other chemically inert, highly impermeable layer. The passivation layers are especially important for device lifetime, as the active device is immersed in the ink. Example Method of Fabrication The print head is fabricated from two silicon apparatus wafers. A first wafer is used to fabricate the nozzle apparatus (the print head wafer) and a second wafer is utilized to fabricate the various ink channels in addition to providing a support means for the first channel (the Ink Channel Wafer). Start with a single silicon wafer, which has a buried epitaxial layer 721 of silicon which is heavily doped with boron. The boron should be doped to preferably 1020 atoms per cm3 of boron or more, and be approximately 3 μm thick. A lightly doped silicon epitaxial layer 722 on top of the boron doped layer 721 should be approximately 8 μm thick and be doped in a manner suitable for the active semiconductor device technology chosen. This is the starting point for the print head wafer. The wafer diameter should be the same as that of the ink channel wafer. Next, fabricate the drive transistors and data distribution circuitry required for each nozzle according to the process chosen, in a standard CMOS layer 718 up until oxide over the first level metal. On top of the CMOS layer 718 is deposited a silicon nitride passivation layer 725. Next, a silicon oxide layer 727 is deposited. The silicon oxide layer 727 is etched utilizing a mask for a copper coil layer. Subsequently, a copper layer 730 is deposited through the mask for the copper coil. The layers 727, 725 also include vias (not shown) for the interconnection of the copper coil layer 730 to the underlying CMOS layer 718. Next, the nozzle chamber 704 ( A final silicon nitride layer 735 is then deposited onto an additional sacrificial layer (not shown) to cover the bare portions of nitride layer 731 to the height of the magnetic material layer 733, utilizing a mask for the magnetic piston and the torsional springs 708. The torsional springs 708, and the magnetic piston 705 (see One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 751 deposit 3 microns of epitaxial silicon heavily doped with boron 721. 2. Deposit 10 microns of epitaxial silicon 722, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process 718. The metal layers are copper instead of aluminum, due to high current densities and subsequent high temperature processing. This step is shown in 4. Deposit 0.5 microns of low stress PECVD silicon nitride (Si3N4) 752. The nitride acts as a dielectric, and etch stop, a copper diffusion barrier, and an ion diffusion barrier. As the speed of operation of the print head is low, the high dielectric constant of silicon nitride is not important, so the nitride layer can be thick compared to sub-micron CMOS back-end processes. 5. Etch the nitride layer using Mask 1. This mask defines the contact vias 753 from the solenoid coil to the second-level metal contacts, as well as the nozzle chamber. This step is shown in 6. Deposit 4 microns of PECVD glass 754. 7. Etch the glass down to nitride or second level metal using Mask 2. This mask defines the solenoid. This step is shown in 8. Deposit a thin barrier layer of Ta or TaN. 9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 10. Electroplate 4 microns of copper 755. 11. Planarize using CMP. Steps 4 to 11 represent a copper dual damascene process, with a 4:1 copper aspect ratio (4 microns high, 1 micron wide). This step is shown in 12. Etch down to silicon using Mask 3. This mask defines the nozzle cavity. This step is shown in 13. Crystallographically etch the exposed silicon using KOH. This etch stops on <111> crystallographic planes 756, and on the boron doped silicon buried layer. This step is shown in 14. Deposit 0.5 microns of low stress PECVD silicon nitride 757. 15. Open the bond pads using Mask 4. 16. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 17. Deposit a thick sacrificial layer 758 (e.g. low stress glass), filling the nozzle cavity. Planarize the sacrificial layer to a depth of 5 microns over the nitride surface. This step is shown in 18. Etch the sacrificial layer to a depth of 6 microns using Mask 5. This mask defines the permanent magnet of the pistons plus the magnet support posts. This step is shown in 19. Deposit 6 microns of permanent magnet material such as neodymium iron boron (NdFeB) 759. Planarize. This step is shown in 20. Deposit 0.5 microns of low stress PECVD silicon nitride 760. 21. Etch the nitride using Mask 6, which defines the spring. This step is shown in 22. Anneal the permanent magnet material at a temperature which is dependant upon the material. 23. Place the wafer in a uniform magnetic field of 2 Tesla (20,000 Gauss) with the field normal to the chip surface. This magnetizes the permanent magnet 24. Mount the wafer on a glass blank and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in 25. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 7. This mask defines the nozzle rim 762. This step is shown in 26. Plasma back-etch through the boron doped layer using Mask 8. This mask defines the nozzle 702, and the edge of the chips. 27. Plasma back-etch nitride up to the glass sacrificial layer through the holes in the boron doped silicon layer. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 28. Strip the adhesive layer to detach the chips from the glass blank. 29. Etch the sacrificial glass layer in buffered HF. This step is shown in 30. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 31. Connect the print heads to their interconnect systems. 32. Hydrophobize the front surface of the print heads. 33. Fill the completed print heads with ink 763 and test them. A filled nozzle is shown in IJ08 In a preferred embodiment, a shutter is actuated by means of a magnetic coil, the coil being used to move the shutter to thereby cause the shutter to open or close. The shutter is disposed between an ink reservoir having an oscillating ink pressure and a nozzle chamber having an ink ejection port defined therein for the ejection of ink. When the shutter is open, ink is allowed to flow from the ink reservoir through to the nozzle chamber and thereby cause an ejection of ink from the ink ejection port. When the shutter is closed, the nozzle chamber remains in a stable state such that no ink is ejected from the chamber. Turning now to A number of coiled springs 830-832 are also provided. The coiled springs store energy as a consequence of the rotation of the shutter 811. Hence, upon deactivation of the electromagnet 819 the coil springs 830-832 act to return the shutter 811 to its closed position. As mentioned previously, the opening and closing of the shutter 811 allows for the flow of ink to the ink nozzle chamber for a subsequent ejection. The coil 819 is activated rotating the arm 816 bringing the surfaces 826, 827 into close contact with the electromagnet 819. The surfaces 826, 827 are kept in contact with the electromagnet 819 by means of utilisation of a keeper current which, due the close proximity between the surfaces 826, 827 is substantially less than that required to initially move the arm 816. The shutter 811 is maintained in the plane by means of a guide 834 which overlaps slightly with an end portion of the shutter 811. Turning now to Next, a copper layer 845 is provided. The copper layer providing a base wiring layer for the electromagnetic array in addition to a lower portion of the pivot 817 and a lower portion of the copper layer being used to form a part of the construction of the guide 834. Next, a NiFe layer 847 is provided which is used for the formation of the internal portions 820 of the electromagnet, in addition to the pivot, aperture arm and shutter 811 in addition to a portion of the guide 834, in addition to the various spiral springs. On top of the NiFe layer 847 is provided a copper layer 849 for providing the top and side windings of the coil 821 in addition to providing the formation of the top portion of guide 834. Each of the layers 845, 847 can be conductively insulated from its surroundings where required through the use of a nitride passivation layer (not shown). Further, a top passivation layer can be provided to cover the various top layers which will be exposed to the ink within the ink reservoir and nozzle chamber. The various levels 845, 849 can be formed through the use of supporting sacrificial structures which are subsequently sacrificially etched away to leave the operable device. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed using the following steps: 1. Using a double sided polished wafer 850 deposit 3 microns of epitaxial silicon heavily doped with boron 840. 2. Deposit 10 microns of epitaxial silicon 841, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process 842. This step is shown in 4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the printheads chips. This step is shown in 5. Crystallographically etch the exposed silicon using KOH. This etch stops on <111> crystallographic planes 851, and on the boron doped silicon buried layer. This step is shown in 6. Deposit 10 microns of sacrificial material 852. Planarize down to oxide using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in 7. Deposit 0.5 microns of silicon nitride (Si3N4) 844. 8. Etch nitride 844 and oxide down to aluminum or sacrificial material using Mask 3. This mask defines the contact vias 823, 824 from the aluminum electrodes to the solenoid, as well as the fixed grill over the nozzle cavity. This step is shown in 9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 10. Spin on 2 microns of resist 853, expose with Mask 4, and develop. This mask defines the lower side of the solenoid square helix, as well as the lowest layer of the shutter grill vertical stop. The resist acts as an electroplating mold. This step is shown in 11. Electroplate 1 micron of copper 854. This step is shown in 12. Strip the resist and etch the exposed copper seed layer. This step is shown in 13. Deposit 0.1 microns of silicon nitride. 14. Deposit 0.5 microns of sacrificial material 855. 15. Etch the sacrificial material down to nitride using Mask 5. This mask defines the solenoid, the fixed magnetic pole, the pivot 817 ( 16. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)]. 17. Spin on 3 microns of resist 856, expose with Mask 6, and develop. This mask defines all of the soft magnetic parts, being the fixed magnetic pole, the pivot 817, the shutter grill, the lever arm 816, the spring posts, and the middle layer of the shutter grill vertical stop. The resist acts as an electroplating mold. This step is shown in 18. Electroplate 2 microns of CoNiFe 857. This step is shown in 19. Strip the resist and etch the exposed seed layer. This step is shown in 20. Deposit 0.1 microns of silicon nitride (Si3N4). 21. Spin on 2 microns of resist 858, expose with Mask 7, and develop. This mask defines the solenoid vertical wire segments, for which the resist acts as an electroplating mold. This step is shown in 22. Etch the nitride down to copper using the Mask 7 resist. 23. Electroplate 2 microns of copper 859. This step is shown in 24. Deposit a seed layer of copper. 25. Spin on 2 microns of resist 860, expose with Mask 8, and develop. This mask defines the upper side of the solenoid square helix, as well as the upper layer of the shutter grill vertical stop. The resist acts as an electroplating mold. This step is shown in 26. Electroplate 1 micron of copper 861. This step is shown in 27. Strip the resist and etch the exposed copper seed layer, and strip the newly exposed resist This step is shown in 28. Deposit 0.1 microns of conformal silicon nitride as a corrosion barrier. 29. Open the bond pads using Mask 9. 30. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 31. Mount the wafer on a glass blank 862 and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer 840. This step is shown in 32. Plasma back-etch the boron doped silicon layer 840 to a depth of 1 micron using Mask 9. This mask defines the nozzle rim 863. This step is shown in 33. Plasma back-etch through the boron doped layer 840 using Mask 10. This mask defines the nozzle 814, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 34. Detach the chips from the glass blank 862. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in 35. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. 36. Connect the printheads to their interconnect systems. 37. Hydrophobize the front surface of the printheads. 38. Fill the completed printheads with ink 864 and test them. A filled nozzle is shown in IJ09 In a preferred embodiment, each nozzle chamber having a nozzle ejection portal further includes two thermal actuators. The first thermal actuator is utilized for the ejection of ink from the nozzle chamber while a second thermal actuator is utilized for pumping ink into the nozzle chamber for rapid ejection of subsequent drops. Normally, ink chamber refill is a result of surface tension effects of drawing ink into a nozzle chamber. In a preferred embodiment, the nozzle chamber refill is assisted by an actuator which pumps ink into the nozzle chamber so as to allow for a rapid refill of the chamber and therefore a more rapid operation of the nozzle chamber in ejecting ink drops. Turning to When it is desired to eject a drop of ink via the port 912, the actuator 916 is activated, as shown in The main actuator 916 is then retracted as illustrated in Next, as illustrated in Next, two alternative procedures are utilized depending on whether the nozzle chamber is to be fired in a next ink ejection cycle or whether no drop is to be fired. The case where no drop is to be fired is illustrated in Where it is desired to fire another drop in the next ink drop ejection cycle, the actuator 916 is activated simultaneously which is illustrated in Hence, it can be seen that the arrangement as illustrated in Turning now to On top of the nitride layer 934 is deposited a first PTFE layer 935 followed by a copper layer 936 and a second PTFE layer 937. These layers are utilized with appropriate masks so as to form the actuators 916, 917. The copper layer 936 is formed near the top surface of the corresponding actuators and is in a serpentine shape. Upon passing a current through the copper layer 936, the copper layer is heated. The copper layer 936 is encased in the PTFE layers 935, 937. PTFE has a much greater coefficient of thermal expansion than copper (770×10−6) and hence is caused to expand more rapidly than the copper layer 936, such that, upon heating, the copper serpentine shaped layer 936 expands via concertinaing at the same rate as the surrounding Teflon layers. Further, the copper layer 936 is formed near the top of each actuator and hence, upon heating of the copper element, the lower PTFE layer 935 remains cooler than the upper PTFE layer 937. This results in a bending of the actuator so as to achieve its actuation effects. The copper layer 936 is interconnected to the lower CMOS layer 934 by means of vias eg 939. Further, the PTFE layers 935/937, which are normally hydrophobic, undergo treatment so as to be hydrophilic. Many suitable treatments exist such as plasma damaging in an ammonia atmosphere. In addition, other materials having considerable properties can be utilized. Turning to One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 950 deposit 3 microns of epitaxial silicon heavily doped with boron 930. 2. Deposit 10 microns of epitaxial silicon 932, either p-type or n-type, depending upon the CMOS process used. 3. Complete a 0.5 micron, one poly, 2 metal CMOS process 933. The metal layers are copper instead of aluminum, due to high current densities and subsequent high temperature processing. This step is shown in 4. Etch the CMOS oxide layers 933 down to silicon or second level metal using Mask 1. This mask defines the nozzle cavity and the bend actuator electrode contact vias 939. This step is shown in 5. Crystallographically etch the exposed silicon using KOH. This etch stops on (111) crystallographic planes 951, and on the boron doped silicon buried layer. This step is shown in 6. Deposit 0.5 microns of low stress PECVD silicon nitride 934 (Si3N4). The nitride acts as an ion diffusion barrier. This step is shown in 7. Deposit a thick sacrificial layer 952 (e.g. low stress glass), filling the nozzle cavity. Planarize the sacrificial layer down to the nitride surface. This step is shown in 8. Deposit 1.5 microns of polytetrafluoroethylene 935 (PTFE). 9. Etch the PTFE using Mask 2. This mask defines the contact vias 939 for the heater electrodes. 10. Using the same mask, etch down through the nitride and CMOS oxide layers to second level metal. This step is shown in 11. Deposit and pattern 0.5 microns of gold 953 using a lift-off process using Mask 3. This mask defines the heater pattern. This step is shown in 12. Deposit 0.5 microns of PTFE 937. 13. Etch both layers of PTFE down to sacrificial glass using Mask 4. This mask defines the gap 954 at the edges of the main actuator paddle and the refill actuator paddle. This step is shown in 14. Mount the wafer on a glass blank 955 and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in 15. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 5. This mask defines the nozzle rim 931. This step is shown in 16. Plasma back-etch through the boron doped layer using Mask 6. This mask defines the nozzle 912, and the edge of the chips. 17. Plasma back-etch nitride up to the glass sacrificial layer through the holes in the boron doped silicon layer. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 18. Strip the adhesive layer to detach the chips from the glass blank. 19. Etch the sacrificial glass layer in buffered HF. This step is shown in 20. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 21. Connect the print heads to their interconnect systems. 22. Hydrophobize the front surface of the print heads. 23. Fill the completed print heads with ink 956 and test them. A filled nozzle is shown in IJ10 In a preferred embodiment, an array of the nozzle arrangements is provided with each of the nozzles being under the influence of a outside pulsed magnetic field. The outside pulsed magnetic field causes selected nozzle arrangements to eject ink from their ink nozzle chambers. Turning initially to A magnetic actuation device 1025 is included and comprises a magnetic soft core 1017 which is surrounded by a nitride coating e.g. 1018. The nitride coating 1018 includes an end protuberance 1027. The magnetic core 1017, operates under the influence of an external pulsed magnetic field. Hence, when the external magnetic field is very high, the actuator 1025 is caused to move rapidly downwards and to thereby cause the ejection of ink from the ink ejection port 1011. Adjacent the actuator 1025 is provided a blocking mechanism 1020 which comprises a thermal actuator which includes a copper resistive circuit having two arms 1022, 1024. A current is passed through the connected arms 1022, 1024 thereby causing them to be heated. The arm 1022, being of a thinner construction undergoes more resistive heating than the arm 1024 which has a much thicker structure. The arm 1022 is also of a serpentine nature and is encased in polytetrafluoroethylene (PTFE) which has a high coefficient of thermal expansion, thereby increasing the degree of expansion upon heating. The copper portions expand with the PTFE portions by means of a concertina-like movement. The arm 1024 has a thinned portion 1029 ( Importantly, the actuator 1020 is located within a cavity 1028 such that the volume of ink flowing past the arm 1022 is extremely low whereas the arm 1024 receives a much larger volume of ink flow during operation. Turning now to Next, the silicon wafer layer 1032 is etched to define the nozzle chamber 1012. The silicon layer 1032 is etched to contain substantially vertical side walls by using high density, low pressure plasma etching such as that available from Surface Technology Systems and subsequently filled with sacrificial material which is later etched away. On top of the silicon layer 1032 is deposited a two level CMOS circuitry layer 1033 which comprises substantially glass in addition to the usual metal and poly layers. A layer 1033 includes the formation of the heater element contacts which can be constructed from copper. The PTFE layer 1035 can be provided as a departure from normal construction with a bottom PTFE layer being first deposited followed by a copper layer 1034 and a second PTFE layer to cover the copper layer 1034. Next, a nitride passivation layer 1036 is provided which acts to provide a passivation surface for the lower layers in addition to providing a base for a soft magnetic Nickel Ferrous layer 1017 which forms the magnetic actuator portion of the actuator 1025. The nitride layer 1036 includes bending portions 1040 ( Next a nitride passivation layer 1039 is provided so as to passivate the top and side surfaces of the nickel iron (NiFe) layer 1017. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:
In a preferred embodiment, there is provided an ink jet nozzle and chamber filled with ink. Within said jet nozzle chamber is located a static coil and a movable coil. When energized, the static and movable coils are attracted-towards one another, loading a spring. The ink drop is ejected from the nozzle when the coils are de-energized. Turn now to The two coils are then energized resulting in an attraction to one another. This results in the movable plate 1115 moving towards the static or fixed plate 1114 as illustrated in Turning to Turning now to As mentioned previously, the various layers of the nozzle 1110 can be constructed in accordance with standard semi-conductor and micro mechanical techniques. These techniques utilise the dual damascene process as mentioned earlier in addition to the utilisation of sacrificial etch layers to provide support for structures which are later released by means of etching the sacrificial layer. The ink can be supplied within the nozzle 1110 by standard techniques such as providing ink channels along the side of the wafer so as to allow the flow of ink into the area under the surface of nozzle plate 1144. Alternatively, ink channel portals can be provided through the wafer by a high density low pressure plasma etch processing system such as that available from surface technology system and known as their Advanced Silicon Etch (ASE) process. The etched portals 1145 being so small that surface tension affects not allow the ink to leak out of the small portal holes. In One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed by the following steps: 1. Using a double sided polished wafer 1122, Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 1150. This step is shown in 2. Deposit 0.5 microns of low stress PECVD silicon nitride (Si3N4) 1123. The nitride acts as a dielectric, and etch stop, a copper diffusion barrier, and an ion diffusion barrier. As the speed of operation of the print head is low, the high dielectric constant of silicon nitride is not important, so the nitride layer can be thick compared to sub-micron CMOS back-end processes. 3. Etch the nitride layer using Mask 1. This mask defines the contact vias 1128, 1129 from the solenoid coil to the second-level metal contacts. This step is shown in 4. Deposit 1 micron of PECVD glass 1152. 5. Etch the glass down to nitride or second level metal using Mask 2. This mask defines first layer of the fixed solenoid 1114 (See 6. Deposit a thin barrier layer of Ta or TaN. 7. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 8. Electroplate 1 micron of copper 1153 9. Planarize using CMP. Steps 2 to 9 represent a copper dual damascene process. This step is shown in 10. Deposit 0.5 microns of low stress PECVD silicon nitride 1154. 11. Etch the nitride layer using Mask 3. This mask defines the defines the vias from the second layer to the first layer of the fixed solenoid 1114. This step is shown in 12. Deposit 1 micron of PECVD glass 1155. 13. Etch the glass down to nitride or copper using Mask 4. This mask defines second layer of the fixed solenoid 1114. This step is shown in 14. Deposit a thin barrier layer and seed layer. 15. Electroplate 1 micron of copper 1156. 16. Planarize using CMP. Steps 10 to 16 represent a second copper dual damascene process. This step is shown in 17. Deposit 0.5 microns of low stress PECVD silicon nitride 1157. 18. Deposit 0.1 microns of PTFE. This is to hydrophobize the space between the two solenoids 1114, 1115 (See 19. Deposit 4 microns of sacrificial material 1158. This forms the space between the two solenoids 1114, 1115. 20. Deposit 0.1 microns of low stress PECVD silicon nitride (Not shown). 21. Etch the nitride layer, the sacrificial layer, the PTFE layer, and the nitride layer of step 17 using Mask 5. This mask defines the vias from the first layer of the moving solenoid 1115 to the second layer the fixed solenoid 1114. This step is shown in 22. Deposit 1 micron of PECVD glass 1159. 23. Etch the glass down to nitride or copper using Mask 6. This mask defines first layer of the moving solenoid. This step is shown in 24. Deposit a thin barrier layer and seed layer. 25. Electroplate 1 micron of copper 1160. 26. Planarize using CMP. Steps 20 to 26 represent a third copper dual damascene process. This step is shown in 27. Deposit 0.1 microns of low stress PECVD silicon nitride 1161. 28. Etch the nitride layer using Mask 7. This mask defines the vias from the second layer the moving solenoid 1115 to the first layer of the moving solenoid. This step is shown in 29. Deposit 1 micron of PECVD glass 1162. 30. Etch the glass down to nitride or copper using Mask 8. This mask defines the second layer of the moving solenoid 1115. This step is shown in 31. Deposit a thin barrier layer and seed layer. 32. Electroplate 1 micron of copper 1163. 33. Planarize using CMP. Steps 27 to 33 represent a fourth copper dual damascene process. This step is shown in 34. Deposit 0.1 microns of low stress PECVD silicon nitride 1164. 35. Etch the nitride using Mask 9. This mask defines the moving solenoid 1115, including its springs 1136-1139, and allows the sacrificial material in the space between the solenoids 1114, 1115 to be etched. It also defines the bond pads. This step is shown in 36. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 37. Deposit 10 microns of sacrificial material 1165. 38. Etch the sacrificial material using Mask 10. This mask defines the nozzle chamber wall 1140, 1141. This step is shown in 39. Deposit 3 microns of PECVD glass 1166. 40. Etch to a depth of 1 micron using Mask 11. This mask defines the nozzle rim 1167. This step is shown in 41. Etch down to the sacrificial layer using Mask 12. This mask defines the roof 1144 of the nozzle 1110 chamber, and the nozzle itself 1111. This step is shown in 42. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 7. This mask defines the ink inlets 1168 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in 43. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in 44. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. 45. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 46. Hydrophobize the front surface of the printheads. 47. Fill the completed printheads with ink 1169 and test them. A filled nozzle is shown in IJ12 In a preferred embodiment, a linear stepper motor is utilized to control a plunger device. The plunger device compressing ink within a nozzle chamber so as to thereby cause the ejection of ink from the chamber on demand. Turning to A linear actuator 1216 is provided for rapidly compressing a nickel ferrous plunger 1218 into the nozzle chamber 1211 so as to compress the volume of ink within chamber 1211 to thereby cause ejection of drops from the ink ejection port 1215. The plunger 1218 is connected to the stepper moving pole device 1216 which is actuated by means of a three phase arrangement of electromagnets 1220 to 1231. The electromagnets are driven in three phases with electro magnets 1220, 1226, 1223 and 1229 being driven in a first phase, electromagnets 1221, 1227, 1224, 1230 being driven in a second phase and electromagnets 1222, 1228, 1225, 1231 being driven in a third phase. The electromagnets are driven in a reversible manner so as to de-actuate plunger 1218 via actuator 1216. The actuator 1216 is guided at one end by a means of guide 1233, 1234. At the other end, the plunger 1218 is coated with a hydrophobic material such as polytetrafluoroethylene (PTFE) which can form a major part of the plunger 1218. The PTFE acts to repel the ink from the nozzle chamber 1211 resulting in the creation of a membrane e.g. 1238, 1239 (See The nozzle arrangement 1210 is therefore operated to eject drops on demand by means of activating the actuator 1216 by appropriately synchronised driving of electromagnets 1220 to 1231. The actuation of the actuator 1216 results in the plunger 1218 moving towards the nozzle ink ejection port 1215 thereby causing ink to be ejected from the port 1215. Subsequently, the electromagnets are driven in reverse thereby moving the plunger in an opposite direction resulting in the in flow of ink from an ink supply connected to the ink inlet port 1214. Preferably, multiple ink nozzle arrangements 1210 can be constructed adjacent to one another to form a multiple nozzle ink ejection mechanism. The nozzle arrangements 1210 are preferably constructed in an array print head constructed on a single silicon wafer which is subsequently diced in accordance with requirements. The diced print heads can then be interconnected to an ink supply which can comprise a through chip ink flow or ink flow from the side of a chip. Turning now to On top of the nitride layer 1242 is constructed various other layers. The wafer layer 1240, the CMOS layer 1241 and the nitride passivation layer 1242 are constructed with the appropriate fires for interconnecting to the above layers. On top of the nitride layer 1242 is constructed a bottom copper layer 1243 which interconnects with the CMOS layer 1241 as appropriate. Next, a nickel ferrous layer 1245 is constructed which includes portions for the core of the electromagnets and the actuator 1216 and guides 1231, 1232. On top of the NiFe layer 1245 is constructed a second copper layer 1246 which forms the rest of the electromagnetic device. The copper layer 1246 can be constructed using a dual damascene process. Next a PTFE layer 1247 is laid down followed by a nitride layer 1248 which includes the side filter portions and side wall portions of the nozzle chamber. In the top of the nitride layer 1248, the ejection port 1215 and the rim 1251 are constructed by means of etching. In the top of the nitride layer 1248 is also provided a number of apertures 1250 which are provided for the sacrificial etching of any sacrificial material used in the construction of the various lower layers including the nitride layer 1248. It will be understood by those skilled in the art of construction of micro-electro-mechanical systems (MEMS) that the various layers 1243, 1245 to 1248 can be constructed by means of utilizing a sacrificial material to deposit the structure of various layers and subsequent etching away of the sacrificial material as to release the structure of the nozzle arrangement 1210. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 1240, complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 1241. This step is shown in 2. Deposit 1 micron of sacrificial material 1260. 3. Etch the sacrificial material and the CMOS oxide layers down to second level metal using Mask 1. This mask defines the contact vias 1261 from the second level metal electrodes to the solenoids. This step is shown in 4. Deposit a barrier layer of titanium nitride (TiN) and a seed layer of copper. 5. Spin on 2 microns of resist 1262, expose with Mask 2, and develop. This mask defines the lower side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in 6. Electroplate 1 micron of copper 1263. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 7. Strip the resist and etch the exposed barrier and seed layers. This step is shown in 8. Deposit 0.1 microns of silicon nitride. 9. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)]. 10. Spin on 3 microns of resist 1264, expose with Mask 3, and develop. This mask defines all of the soft magnetic parts, being the fixed magnetic pole of the solenoids, the moving poles of the linear actuator, the horizontal guides, and the core of the ink plunger. The resist acts as an electroplating mold. This step is shown in 11. Electroplate 2 microns of CoNiFe 1265. This step is shown in 12. Strip the resist and etch the exposed seed layer. This step is shown in 13. Deposit 0.1 microns of silicon nitride (Si3N4) (not shown). 14. Spin on 2 microns of resist 1266, expose with Mask 4, and develop. This mask defines the solenoid vertical wire segments 1267, for which the resist acts as an electroplating mold. This step is shown in 15. Etch the nitride down to copper using the Mask 4 resist. 16. Electroplate 2 microns of copper 1268. This step is shown in 17. Deposit a seed layer of copper. 18. Spin on 2 microns of resist 1270, expose with Mask 5, and develop. This mask defines the upper side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in 19. Electroplate 1 micron of copper 1271. This step is shown in 20. Strip the resist and etch the exposed copper seed layer, and strip the newly exposed resist. This step is shown in 21. Open the bond pads using Mask 6. 22. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 23. Deposit 5 microns of PTFE 1272. 24. Etch the PTFE down to the sacrificial layer using Mask 7. This mask defines the ink plunger. This step is shown in 25. Deposit 8 microns of sacrificial material 1273. Planarize using CMP to the top of the PTFE ink pusher. This step is shown in 26. Deposit 0.5 microns of sacrificial material 1275. This step is shown in 27. Etch all layers of sacrificial material using Mask 8. This mask defines the nozzle chamber wall 1236, 1237. This step is shown in 28. Deposit 3 microns of PECVD glass 1276. 29. Etch to a depth of (approx.) 1 micron using Mask 9. This mask defines the nozzle rim 1251. This step is shown in 30. Etch down to the sacrificial layer using Mask 10. This mask defines the roof of the nozzle chamber, the nozzle 1215, and the sacrificial etch access holes 1250. This step is shown in 31. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 11. Continue the back-etch through the CMOS glass layers until the sacrificial layer is reached. This mask defines the ink inlets 1280 which are etched through the wafer. The wafer is also diced by this etch This step is shown in 32. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch This step is shown in 33. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. 34. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 35. Hydrophobize the front surface of the printheads. 36. Fill the completed printheads with ink 1281 and test them. A filled nozzle is shown in IJ13 In a preferred embodiment, an ink jet nozzle chamber is provided having a shutter mechanism which open and closes over a nozzle chamber. The shutter mechanism includes a ratchet drive which slides open and close. The ratchet drive is driven by a gearing mechanism which in turn is driven by a drive actuator which is activated by passing an electric current through the drive actuator in a magnetic field. The actuator force is “geared down” so as to drive a ratchet and pawl mechanism to thereby open and shut the shutter over a nozzle chamber. Turning to The nozzle arrangement 1310 can be constructed using a two level poly process which can be a standard micro-electro mechanical system production technique (MEMS). The plate 1317 can be constructed from a first level polysilicon and the retainers 1322 to 1325 can be constructed from a lower first level poly portion and a second level poly portion, as it is more apparent from the exploded perspective view illustrated in The bottom circuit of plate 1317 includes a number of pits which are provided on the bottom surface of plate 1317 so as to reduce stiction effects. The ratchet mechanism 1320 is driven by a gearing arrangement which includes first gear wheel 1330, second gear wheel 1331 and third gear wheel 1332. These gear wheels 1330 to 1332 are constructed using two level poly with each gear wheel being constructed around a corresponding central pivot 1335 to 1337. The gears 1330 to 1332 operate to gear down the ratchet speed with the gears being driven by a gear actuator mechanism 1340. Turning to Returning to Turning to The bottom boron layer 1313 can be formed from the processing step of back etching a silicon wafer utilizing a buried epitaxial boron doped layer as the etch stop. Further processing of the boron layer can be undertaken so as to define the nozzle hole 1315 which can include a nozzle rim 1314. The next layer is a silicon layer 1352 which normally sits on top of the boron doped layer 1313. The silicon layer 1352 includes an anisotropically etched pit 1312 so as to define the structure of the nozzle chamber. On top of the silicon layer 1352 is provided a glass layer 1354 which includes the various electrical circuitry (not shown) for driving the actuators. The layer 1354 is passivated by means of a nitride layer 1356 which includes trenches 1357 for passivating the side walls of glass layer 1354. On top of the passivation layer 1356 is provided a first level polysilicon layer 1358 which defines the shutter and various cog wheels. The second poly layer 1359 includes the various retainer mechanisms and gear wheel 1331. Next, a copper layer 1360 is provided for defining the copper circuit actuator. The copper 1360 is interconnected with lower portions of glass layer 1354 for forming the circuit for driving the copper actuator. The nozzle chamber 1310 can be constructed using the standard MEMS processes including forming the various layers using the sacrificial material such as silicon dioxide and subsequently sacrificially etching the lower layers away. Subsequently, wafers that contain a series of print heads can be diced into separate printheads mounted on a wall of an ink supply chamber having a piezo electric oscillator actuator for the control of pressure in the ink supply chamber. Ink is then ejected on demand by opening the shutter plate 1317 during periods of high oscillation pressure so as to eject ink. The nozzles being actuated by means of placing the printhead in a strong magnetic field using permanent magnets or electromagnetic devices and driving current through the actuators e.g. 1340, 1350 as required to open and close the shutter and thereby eject drops of ink on demand. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron 1313. 2. Deposit 10 microns of n/n+ epitaxial silicon 1352. Note that the epitaxial layer is substantially thicker than required for CMOS. This is because the nozzle chambers are crystallographically etched from this layer. This step is shown in 3. Crystallographically etch the epitaxial silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol) 1370 using MEMS Mask 1. This mask defines the nozzle cavity. This etch stops on (111) crystallographic planes, and on the boron doped silicon buried layer. This step is shown in 4. Deposit 12 microns of low stress sacrificial oxide 1371. Planarize down to silicon using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in 5. Begin fabrication of the drive transistors, data distribution, and timing circuits using a CMOS process. The MEMS processes which form the mechanical components of the inkjet are interleaved with the CMOS device fabrication steps. The example given here is of a 1 micron, 2 poly, 2 metal retrograde P-well process. The mechanical components are formed from the CMOS polysilicon layers. For clarity, the CMOS active components are omitted. 6. Grow the field oxide using standard LOCOS techniques to a thickness of 0.5 microns. As well as the isolation between transistors, the field oxide is used as a MEMS sacrificial layer, so inkjet mechanical details are incorporated in the active area mask. The MEMS features of this step are shown in 7. Perform the PMOS field threshold implant. The MEMS fabrication has no effect on this step except in calculation of the total thermal budget. 8. Perform the retrograde P-well and NMOS threshold adjust implants using the P-well mask. The MEMS fabrication has no effect on this step except in calculation of the total thermal budget. 9. Perform the PMOS N-tub deep phosphorus punchthrough control implant and shallow boron implant. The MEMS fabrication has no effect on this step except in calculation of the total thermal budget. 10. Deposit and etch the first polysilicon layer 1358. As well as gates and local connections, this layer includes the lower layer of MEMS components. This includes the lower layer of gears, the shutter, and the shutter guide. It is preferable that this layer be thicker than the normal CMOS thickness. A polysilicon thickness of 1 micron can be used. The MEMS features of this step are shown in 11. Perform the NMOS lightly doped drain (LDD) implant This process is unaltered by the inclusion of MEMS in the process flow. 12. Perform the oxide deposition and RIE etch for polysilicon gate sidewall spacers. This process is unaltered by the inclusion of MEMS in the process flow. 13. Perform the NMOS source/drain implant The extended high temperature anneal time to reduce stress in the two polysilicon layers must be taken into account in the thermal budget for diffusion of this implant. Otherwise, there is no effect from the MEMS portion of the chip. 14.Perform the PMOS source/drain implant As with the NMOS source/drain implant, the only effect from the MEMS portion of the chip is on thermal budget for diffusion of this implant. 15. Deposit 1 micron of glass 1372 as the first interlevel dielectric and etch using the CMOS contacts mask. The CMOS mask for this level also contains the pattern for the MEMS inter-poly sacrificial oxide. The MEMS features of this step are shown in 16. Deposit and etch the second polysilicon layer 1359. As well as CMOS local connections, this layer includes the upper layer of MEMS components. This includes the upper layer of gears and the shutter guides. A polysilicon thickness of 1 micron can be used. The MEMS features of this step are shown in 17. Deposit 1 micron of glass 1373 as the second interlevel dielectric and etch using the CMOS via 1 mask. The CMOS mask for this level also contains the pattern for the MEMS actuator contacts. 18. Metal 1 1374 deposition and etch Metal 1 should be non-corrosive in water, such as gold or platinum, if it is to be used as the Lorenz actuator. The MEMS features of this step are shown in 19. Third interlevel dielectric deposition 1375 and etch as shown in 20. Metal 2 1379 deposition and etch. This is the standard CMOS metal 2. The mask pattern includes no metal 2 in the MEMS area. 21. Deposit 0.5 microns of silicon nitride (Si3N4) 1376 and etch using MEMS Mask 2. This mask defines the region of sacrificial oxide etch performed in step 26. The silicon nitride aperture is substantially undersized, as the sacrificial oxide etch is isotropic. The CMOS devices must be located sufficiently far from the MEMS devices that they are not affected by the sacrificial oxide etch The MEMS features of this step are shown in 22. Mount the wafer on a glass blank 1377 and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. The MEMS features of this step are shown in 23. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using MEMS Mask 3. This mask defines the nozzle rim 1314. The MEMS features of this step are shown in 24. Plasma back-etch through the boron doped layer using MEMS Mask 4. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. The MEMS features of this step are shown in 25. Detach the chips from the glass blank. Strip the adhesive. This step is shown in 26. Etch the sacrificial oxide using vapor phase etching (VPE) using an anhydrous HF/methanol vapor mixture. The use of a dry etch avoids problems with stiction. This step is shown in 27. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. The package also contains the permanent magnets which provide the 1 Tesla magnetic field for the Lorenz actuators formed of metal 1. 28. Connect the printheads to their interconnect systems. 29. Hydrophobize the front surface of the print heads. 30. Fill the completed printheads with ink 1378 and test them. A filled nozzle is shown in IJ14 In a preferred embodiment, there is provided an ink jet nozzle which incorporates a plunger that is surrounded by an electromagnetic device. The plunger is made from a magnetic material such that upon activation of the magnetic device, the plunger is forced towards a nozzle outlet port thereby resulting in the ejection of ink from the outlet port. Upon deactivation of the electromagnet the plunger returns to its rest position due to of a series springs constructed to return the electromagnet to its rest position. An electromagnetic device is constructed around the plunger 1414 and includes outer soft magnetic material 1419 which surrounds a copper current carrying wire core 1420 with a first end of the copper coil 1420 connected to a first portion of a nickel-ferrous material and a second end of the copper coil is connected to a second portion of the nickel-ferrous material. The circuit being further formed by means of vias (not shown) connecting the current carrying wire to lower layers which can take the structure of standard CMOS fabrication layers. Upon activation of the electromagnet, the tapered plunger portions 1416 are attracted to the electromagnet. The tapering allows for the forces to be resolved by means of downward movement of the overall plunger 1414, the downward movement thereby causing the ejection of ink from ink ejection port 1412. In due of course, the plunger will move to a stable state having its top surface substantially flush with the electromagnet Upon turning the power off, the plunger 1414 will return to its original position as a result of energy stored within that nitride springs 1417. The nozzle chamber 1411 is refilled by inlet holes 1422 from the ink reservoir 1423. Turning now to Further, the tapered end portions of the nickel-ferrous material can be formed so that the use of a half-tone mask having an intensity pattern corresponding to the desired bottom tapered profile of plunger 1414. The half-tone mask can be used to half-tone a resist so that the shape is transferred to the resist and subsequently to a lower layer, such as sacrificial glass on top of which is laid the nickel-ferrous material which can be finally planarized using chemical mechanical planarization techniques. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed using the following steps: 1. Using a double sided polished wafer 1450 deposit 3 microns of epitaxial silicon heavily doped with boron 1430. 2. Deposit 10 microns of epitaxial silicon 1432, either p-type or n-type, depending upon the CMOS process used. 3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 1433. This step is shown in 4. Etch the CMOS oxide layers 1433 down to silicon 1432 or aluminum using Mask 1. This mask defines the nozzle chamber 1411 and the edges of the print heads chips. 5. Plasma etch the silicon 1432 down to the boron doped buried layer, using oxide from step 4 as a mask. This etch does not substantially etch the aluminum. This step is shown in 6. Deposit 0.5 microns of silicon nitride 1434 (Si3N4). 7. Deposit 12 microns of sacrificial material 1451. 8. Planarize down to nitride using CMP. This fills the nozzle chamber level to the chip surface. This step is shown in 9. Etch nitride 1434 and CMOS oxide layers down to second level metal using Mask 2. This mask defines the vias for the contacts from the second level metal electrodes to the two halves of the split fixed magnetic pole. This step is shown in 10. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)]. 11. Spin on 5 microns of resist 1452, expose with Mask 3, and develop. This mask defines the lowest layer of the split fixed magnetic pole, and the thinnest rim of the magnetic plunger. The resist acts as an electroplating mold. This step is shown in 12. Electroplate 4 microns of CoNiFe 1436. This step is shown in 13. Deposit 0.1 microns of silicon nitride (Si3N4). 14. Etch the nitride layer using Mask 4. This mask defines the contact vias from each end of the solenoid coil to the two halves of the split fixed magnetic pole. 15. Deposit a seed layer of copper. 16. Spin on 5 microns of resist 1454, expose with Mask 5, and develop. This mask defines the solenoid spiral coil and the spring posts, for which the resist acts as an electroplating mold. This step is shown in 17. Electroplate 4 microns of copper 1437. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 18. Strip the resist 1454 and etch the exposed copper seed layer. This step is shown in 19. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 20. Deposit 0.1 microns of silicon nitride. This layer of nitride provides corrosion protection and electrical insulation to the copper coil. 21. Etch the nitride layer using Mask 6. This mask defines the regions of continuity between the lower and the middle layers of CoNiFe. 22. Spin on 4.5 microns of resist 1455, expose with Mask 6, and develop. This mask defines the middle layer of the split fixed magnetic pole, and the middle rim of the magnetic plunger. The resist forms an electroplating mold for these parts. This step is shown in 23. Electroplate 4 microns of CoNiFe 1456. The lowest layer of CoNiFe acts as the seed layer. This step is shown in 24. Deposit a seed layer of CoNiFe. 25. Spin on 4.5 microns of resist 1457, expose with Mask 7, and develop. This mask defines the highest layer of the split fixed magnetic pole and the roof of the magnetic plunger. The resist forms electroplating mold for these parts. This step is shown in 26. Electroplate 4 microns of CoNiFe 1458. This step is shown in 27. Deposit 1 micron of sacrificial material 1459. 28. Etch the sacrificial material 1459 using Mask 8. This mask defines the contact points of the nitride springs to the split fixed magnetic poles and the magnetic plunger. This step is shown in 29. Deposit 0.1 microns of low stress silicon nitride 1460. 30. Deposit 0.1 microns of high stress silicon nitride 1461. These two layers 1460, 1461 of nitride form pre-stressed spring which lifts the magnetic plunger 1414 out of core space of the fixed magnetic pole. 31. Etch the two layers 1460, 1461 of nitride using Mask 9. This mask defines the nitride spring 1440. This step is shown in 32. Mount the wafer on a glass blank 1462 and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer 1430. This step is shown in 33. Plasma back-etch the boron doped silicon layer to a depth of (approx.) 1 micron using Mask 10. This mask defines the nozzle rim 1431. This step is shown in 34. Plasma back-etch through the boron doped layer using Mask 11. This mask defines the nozzle 1412, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank This step is shown in 35. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers. The nitride spring 1440 is released in this step, lifting the magnetic plunger out of the fixed magnetic pole by 3 microns. This step is shown in 36. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 37. Connect the printheads to their interconnect systems. 38. Hydrophobize the front surface of the printheads. 39. Fill the completed printheads with ink 1463 and test them. A filled nozzle is shown in IJ15 In the present invention, a magnetically actuated ink jet print nozzle is provided for the ejection of ink from an ink chamber. The magnetically actuated ink jet utilises utilizes a linear spring to increase the travel of a shutter grill which blocks any ink pressure variations in a nozzle when in a closed position. However when the shutter is open, pressure variations are directly transmitted to the nozzle chamber and can result in the ejection of ink from the chamber. An oscillating ink pressure within an ink reservoir is used therefore to eject ink from nozzles having an open shutter grill. In An electromagnetic actuator is utilized to attract the moveable bar 1516 generally in the direction of arrow 1525. The electromagnetic actuator consists of a series of soft iron claws 1524 around which is formed a copper coil wire 1526. The electromagnetic actuators can comprise a series of actuators 1528-1530 interconnected via the copper coil windings. Hence, when it is desired to open the shutters 1512-1513 the coil 1526 is activated resulting in an attraction of bar 1516 towards the electromagnets 1528-1530. The attraction results in a corresponding interaction with linear springs 1520, 1521 and a movement of shutters 1512, 1513 to an open position as illustrated in The linear springs 1520, 1521 are designed to increase the movement of the shutter as a result of actuation by a factor of eight. A one micron motion of the bar towards the electromagnets will result in an eight micron sideways movement. This dramatically improves the efficiency of the system, as any magnetic field falls off strongly with distance, while the linear springs have a linear relationship between motion in one axis and the other. The use of the linear springs 1520, 1521 therefore allows the relatively large motion required to be easily achieved. The surface of the wafer is directly immersed in an ink reservoir or in relatively large ink channels. An ultrasonic transducer (for example, a piezoelectric transducer), not shown, is positioned in the reservoir. The transducer oscillates the ink pressure at approximately 100 KHz. The ink pressure oscillation is sufficient that ink drops would be ejected from the nozzle when it is not blocked by the shutters 1512, 1513. When data signals distributed on the print head indicate that a particular nozzle is to eject a drop of ink, the drive transistor for that nozzle is turned on. This energises energizes the actuators 1528-1530, which moves the shutters 1512, 1513 so that they are not blocking the ink chamber. The peak of the ink pressure variation causes the ink to be squirted out of the nozzle. As the ink pressure goes negative, ink is drawn back into the nozzle, causing drop break-off. The shutters 1512, 1513 are kept open until the nozzle is refilled on the next positive pressure cycle. They are then shut to prevent the ink from being withdrawn from the nozzle on the next negative pressure cycle. Each drop ejection takes two ink pressure cycles. Preferably half of the nozzles should eject drops in one phase, and the other half of the nozzles should eject drops in the other phase. This minimizes the pressure variations which occur due to a large number of nozzles being actuated. The amplitude of the ultrasonic transducer can be further altered in response to the viscosity of the ink (which is typically affected by temperature), and the number of drops which are to be ejected in a current cycle. This amplitude adjustment can be used to maintain consistent drop size in varying environmental conditions. In The device is manufactured on <100> silicon with a buried boron etch stop layer 1540, but rotated 45° in relation to the <010> and <001> planes. Therefore, the <111> planes which stop the crystallographic etch of the nozzle chamber form a 45° rectangle which superscribes the slots in the fixed grill. This etch will proceed quite slowly, due to limited access of etchant to the silicon. However, the etch can be performed at the same time as the bulk silicon etch which thins the bottom of the wafer. In A subsequent layer 1542 is constructed for the provision of drive transistors and printer logic and can comprise a two level metal CMOS processing layer 1542. The CMOS processing layer is covered by a nitride layer 1543 which includes portions 1544 which cover and protect the side walls of the CMOS layer 1542. The copper layer 1545 can be constructed utilizing a dual damascene process. Finally, a soft metal (NiFe) layer 1546 is provided for forming the rest of the actuator. Each of the layers 1544, 1545 are separately coated by a nitride insulating layer (not shown) which provides passivation and insulation and can be a standard 0.1 micron process. The arrangement of One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 1550 deposit 3 microns of epitaxial silicon heavily doped with boron 1540. 2. Deposit 10 microns of epitaxial silicon 1541, either p-type or n-type, depending upon the CMOS process used. 3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer 1550 at this step are shown in 4. Etch the CMOS oxide layers 1541 down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber 1534, and the edges of the print head chips. This step is shown in 5. Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in 6. Deposit 12 microns of sacrificial material 1551. Planarize down to oxide using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in 7. Deposit 0.5 microns of silicon nitride (Si3N4) 1552. 8. Etch nitride 1552 and oxide down to aluminum 1542 or sacrificial material 1551 using Mask 3. This mask defines the contact vias from the aluminum electrodes to the solenoid, as well as the fixed grill over the nozzle cavity. This step is shown in 9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 10. Spin on 2 microns of resist 1553, expose with Mask 4, and develop. This mask defines the lower side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in 11. Electroplate 1 micron of copper 1554. This step is shown in 12. Strip the resist 1553 and etch the exposed copper seed layer. This step is shown in 13. Deposit 0.1 microns of silicon nitride. 14. Deposit 0.5 microns of sacrificial material 1556. 15. Etch the sacrificial material 1556 down to nitride 1552 using Mask 5. This mask defines the solenoid, the fixed magnetic pole, and the linear spring anchor. This step is shown in 16. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)]. 17. Spin on 3 microns of resist 1557, expose with Mask 6, and develop. This mask defines all of the soft magnetic parts, being the U shaped fixed magnetic poles, the linear spring, the linear spring anchor, and the shutter grill. The resist acts as the electroplating mold. This step is shown in 18. Electroplate 2 microns of CoNiFe 1558. This step is shown in 19. Strip the resist 1557 and etch the exposed seed layer. This step is shown in 20. Deposit 0.1 microns of silicon nitride (Si3N4). 21. Spin on 2 microns of resist 1559, expose with Mask 7, and develop. This mask defines the solenoid vertical wire segments, for which the resist acts as an electroplating mold. This step is shown in 22. Etch the nitride down to copper using the Mask 7 resist. 23. Electroplate 2 microns of copper 1560. This step is shown in 24. Deposit a seed layer of copper. 25. Spin on 2 microns of resist 1561, expose with Mask 8, and develop. This mask defines the upper side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in 26. Electroplate 1 micron of copper 1562. This step is shown in 27. Strip the resist 1559 and 1561 and etch the exposed copper seed layer, and strip the newly exposed resist. This step is shown in 28. Deposit 0.1 microns of conformal silicon nitride as a corrosion barrier. 29. Open the bond pads using Mask 9. 30. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 31. Mount the wafer on a glass blank 1563 and back-etch the wafer 1550 using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer 1540. This step is shown in 32. Plasma back-etch the boron doped silicon layer 1540 to a depth of 1 micron using Mask 9. This mask defines the nozzle rim 1564. This step is shown in 33. Plasma back-etch through the boron doped layer using Mask 10. This mask defines the nozzle 1536, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in 34. Detach the chips from the glass blank 1563. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in 35. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. 36. Connect the print heads to their interconnect systems. 37. Hydrophobize the front surface of the print heads. 38. Fill the completed print heads with ink 1565 and test them. A filled nozzle is shown in IJ16 A preferred embodiment uses a Lorenz force on a current carrying wire in a magnetic field to actuate a diaphragm for the injection of ink from a nozzle chamber via a nozzle hole. The magnetic field is static and is provided by a permanent magnetic yoke around the nozzles of an ink jet head. Referring initially to In The movement of the diaphragm 1611 results from a Lorenz interaction between the coil current and the magnetic field. The diaphragm 1611 is corrugated so that the diaphragm motion occurs as an elastic bending motion. This is important as a flat diaphragm may be prevented from flexing by tensile stress. When data signals distributed on the printhead indicate that a particular nozzle is to eject a drop of ink, the drive transistor for that nozzle is turned on. This energizes the coil 1614, causing elastic deformation of the diaphragm 1611 downwards, ejecting ink. After approximately 3 μs, the coil current is turned off, and the diaphragm 1611 returns to its quiescent position The diaphragm return ‘sucks’ some of the ink back into the nozzle, causing the ink ligament connecting the ink drop to the ink in the nozzle to thin. The forward velocity of the drop and backward velocity of the ink in the chamber 1618 are resolved by the ink drop breaking off from the ink in the nozzle. The ink drop then continues towards the recording medium. Ink refill of the nozzle chamber 1618 is via the two slots 1622, 1623 at either side of the diaphragm. The ink refill is caused by the surface tension of the ink meniscus at the nozzle. Turning to After development, as is illustrated in In The nozzle 1610 can be formed as part of an array of nozzles formed on a single wafer. After construction, the wafer creating nozzles 1610 can be bonded to a second ink supply wafer having ink channels for the supply of ink such that the nozzle 1610 is effectively supplied with an ink reservoir on one side and ejects ink through the hole 1613 onto print media or the like on demand as required. The nozzle chamber 1618 is formed using an anisotropic crystallographic etch of the silicon substrate. Etchant access to the substrate is via the slots 1622, 1623 at the sides of the diaphragm. The device is manufactured on <100> silicon (with a buried boron etch stop layer), but rotated 45° in relation to the <010> and <001> planes. Therefore, the <111> planes which stop the crystallographic etch of the nozzle chamber form a 45° rectangle which superscribes the slot in the nitride layer. This etch will proceed quite slowly, due to limited access of etchant to the silicon. However, the etch can be performed at the same time as the bulk silicon etch which thins the wafer. The drop firing rate is around 7 KHz. The ink jet head is suitable for fabrication as a monolithic page wide print head. The illustration shows a single nozzle of a 1600 dpi print head in ‘down shooter’ configuration. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 1650 deposit 3 microns of epitaxial silicon heavily doped with boron 1640. 2. Deposit 10 microns of epitaxial silicon 1641, either p-type or n-type, depending upon the CMOS process used. 3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 1642. This step is shown in 4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the print heads chips. This step is shown in 5. Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystallographic planes 1651, and on the boron doped silicon buried layer. This step is shown in 6. Deposit 12 microns of sacrificial material (polyimide) 1652. Planarize down to oxide using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in 7. Deposit 1 micron of (sacrificial) photosensitive polyimide. 8. Expose and develop the photosensitive polyimide using Mask 2. This mask is a gray-scale mask which defines the concertina ridges of the flexible membrane containing the central part of the solenoid. The result of the etch is a series of triangular ridges 1653 across the whole length of the ink pushing membrane. This step is shown in 9. Deposit 0.1 microns of PECVD silicon nitride (Si3N4) (Not shown). 10. Etch the nitride layer using Mask 3. This mask defines the contact vias 1654 from the solenoid coil to the second-level metal contacts. 11. Deposit a seed layer of copper. 12. Spin on 2 microns of resist 1656, expose with Mask 4, and develop. This mask defines the coil of the solenoid. The resist acts as an electroplating mold. This step is shown in 13. Electroplate 1 micron of copper 1655. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. 14. Strip the resist and etch the exposed copper seed layer 1657. This step is shown in 15. Deposit 0.1 microns of silicon nitride (Si3N4) (Not shown). 16. Etch the nitride layer using Mask 5. This mask defines the edges of the ink pushing membrane and the bond pads. 17. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 18. Mount the wafer on a glass blank 1658 and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in 19. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 6. This mask defines the nozzle rim 1659. This step is shown in 20. Plasma back-etch through the boron doped layer using Mask 7. This mask defines the nozzle 1613, and the edge of the chips. At this stage, the chips are still mounted on the glass blank. This step is shown in 21. Strip the adhesive layer to detach the chips from the glass blank. Etch the sacrificial layer. This process completely separates the chips. This step is shown in 22. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 23. Connect the printheads to their interconnect systems. 24. Hydrophobize the front surface of the printheads. 25. Fill with ink 1660, apply a strong magnetic field in the plane of the chip surface, and test the completed printheads. A filled nozzle is shown in IJ17 In a preferred embodiment, an oscillating ink reservoir pressure is used to eject ink from ejection nozzles. Each nozzle has an associated shutter which normally blocks the nozzle. The shutter is moved away from the nozzle by an actuator whenever an ink drop is to be fired. Turning initially to A bottom nitride layer 1716 is constructed on top of the CMOS layer 1713 so as to cover, protect and passivate the CMOS layer 1713 from subsequent etching processes. Subsequently, there is provided a copper heater layer 1718 which is sandwiched between two polytetrafluoroethylene (PTFE) layers 1719, 1720. The copper layer 1718 is connected to lower CMOS layer 1713 through vias 1725, 1726. The copper layer 1718 and PTFE layers 1719, 1720 are encapsulated within nitride borders e.g. 1728 and nitride top layer 1729 which includes an ink ejection portal 1730 in addition to a number of sacrificial etched access holes 1732 which are of a smaller dimension than the ejection portal 1730 and are provided for allowing access of a etchant to lower sacrificial layers thereby allowing the use of a etchant in the construction of layers, 1718, 1719, 1720 and 1728. Turning now to The nozzles 1730 are in connected to ink chambers which contain the actuators 1735. These chambers are connected to ink supply channels 1736 which are etched through the silicon wafer. The ink supply channels 1736 are substantially wider than the nozzles 1730, to reduce the fluidic resistance to the ink pressure wave. The ink channels 1736 are connected to an ink reservoir. An ultrasonic transducer (for example, a piezoelectric transducer) is positioned in the reservoir. The transducer oscillates the ink pressure at approximately 100 KHz. The ink pressure oscillation is sufficient that ink drops would be ejected from the nozzle were it not blocked by the shutter 1731. The shutters are moved by a thermoelastic actuator 1735. The actuators are formed as a coiled serpentine copper heater 1723 embedded in polytetrafluoroethylene (PTFE) 1719, 1720. PTFE has a very high coefficient of thermal expansion (approximately 770×10−6). The current return trace 1722 from the heater 1723 is also embedded in the PTFE actuator 1735, the current return trace 1722 is made wider than the heater trace 1723 and is not serpentine. Therefore, it does not heat the PTFE as much as the serpentine heater 1723 does. The serpentine heater 1723 is positioned along the inside edge of the PTFE coil, and the return trace is positioned on the outside edge. When actuated, the inside edge becomes hotter than the outside edge, and expands more. This results in the actuator 1735 uncoiling. The heater layer 1723 is etched in a serpentine manner both to increase its resistance, and to reduce its effective tensile strength along the length of the actuator. This is so that the low thermal expansion of the copper does not prevent the actuator from expanding according to the high thermal expansion characteristics of the PTFE. By varying the power applied to the actuator 1735, the shutter 1731 can be positioned between the fully on and fully off positions. This may be used to vary the volume of the ejected drop. Drop volume control may be used either to implement a degree of continuous tone operation, to regulate the drop volume, or both. When data signals distributed on the printhead indicate that a particular nozzle is turned on, the actuator 1735 is energized, which moves the shutter 1731 so that it is not blocking the ink chamber. The peak of the ink pressure variation causes the ink to be squirted out of the nozzle 1730. As the ink pressure goes negative, ink is drawn back into the nozzle, causing drop break-off. The shutter 1731 is kept open until the nozzle is refilled on the next positive pressure cycle. It is then shut to prevent the ink from being withdrawn from the nozzle on the next negative pressure cycle. Each drop ejection takes two ink pressure cycles. Preferably half of the nozzles 1710 should eject drops in one phase, and the other half of the nozzles should eject drops in the other phase. This minimises the pressure variations which occur due to a large number of nozzles being actuated. The amplitude of the ultrasonic transducer can be altered in response to the viscosity of the ink (which is typically affected by temperature), and the number of drops which are to be ejected in the current cycle. This amplitude adjustment can be used to maintain consistent drop size in varying environmental conditions. The drop firing rate can be around 50 KHz. The ink jet head is suitable for fabrication as a monolithic page wide printhead Return again to A thin sacrificial glass layer is then laid down on top of nitride layers 1716 followed by a first PTFE layer 1719, the copper layer 1718 and a second PTFE layer 1720. Then a sacrificial glass layer is formed on top of the PTFE layer and etched to a depth of a few microns to form the nitride border regions 1728. Next the top layer 1729 is laid down over the sacrificial layer using the mask for forming the various holes including the processing step of forming the rim 1740 on nozzle 1730. The sacrificial glass is then dissolved away and the channel 1715 formed through the wafer by means of utilisation of high density low pressure plasma etching such as that available from Surface Technology Systems. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed using the following steps: 1. Using a double sided polished wafer 1712, Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 1713. The wafer is passivated with 0.1 microns of silicon nitride 1716. This step is shown in 2. Etch nitride and oxide down to silicon using Mask 1. This mask defines the nozzle inlet below the shutter. This step is shown in 3. Deposit 3 microns of sacrificial material 1750 (e.g. aluminum or photosensitive polyimide) 4. Planarize the sacrificial layer to a thickness of 1 micron over nitride. This step is shown in 5. Etch the sacrificial layer using Mask 2. This mask defines the actuator anchor point 1751. This step is shown in 6. Deposit 1 micron of PTFE 1752. 7. Etch the PTFE, nitride, and oxide down to second level metal using Mask 3. This mask defines the heater vias 1725, 1726. This step is shown in 8. Deposit the heater 1753, which is a 1 micron layer of a conductor with a low Young's modulus, for example aluminum or gold. 9. Pattern the conductor using Mask 4. This step is shown in 10. Deposit 1 micron of PTFE 1754. 11. Etch the PTFE down to the sacrificial layer using Mask 5. This mask defines the actuator and shutter This step is shown in 12. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 13. Deposit 3 microns of sacrificial material 1755. Planarize using CMP 14. Etch the sacrificial material using Mask 6. This mask defines the nozzle chamber wall 1728. This step is shown in 15. Deposit 3 microns of PECVD glass 1756. 16. Etch to a depth of (approx.) 1 micron using Mask 7. This mask defines the nozzle rim 1740. This step is shown in 17. Etch down to the sacrificial layer using Mask 6. This mask defines the roof of the nozzle chamber, the nozzle 1730, and the sacrificial etch access holes 1732. This step is shown in 18. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 7. This mask defines the ink inlets 1715 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in 19. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in 20. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. 21. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 22. Hydrophobize the front surface of the printheads. 23. Fill the completed printheads with ink 1757 and test them. A filled nozzle is shown in IJ18 In a preferred embodiment, an inkjet printhead includes a shutter mechanism which interconnects the nozzle chamber with an ink supply reservoir, the reservoir being under an oscillating ink pressure. Hence, when the shutter is open, ink is forced through the shutter mechanism and out of the nozzle chamber. Closing the shutter mechanism results in the nozzle chamber remaining in a stable state and not ejecting any ink from the chamber. Turning initially to Nitride layers, including side walls 1840 and top portion 1841, are constructed to form the rest of a nozzle chamber 1810. The top surface includes an ink ejection nozzle 1842 in addition to a number of smaller nozzles 1843 which are provided for sacrificial etching purposes. The nozzles 1843 are much smaller than the nozzle 1842 such that, during operation, surface tension effects restrict any ejection of ink from the nozzles 1843. In operation, the ink supply channel 1819 is driven with an oscillating ink pressure. The oscillating ink pressure can be induced by means of driving a piezoelectric actuator in an ink chamber. When it is desired to eject a drop from the nozzle 1842, the shutter is opened forcing the drop of ink out of the nozzle 1842 during the next high pressure cycle of the oscillating ink pressure. The ejected ink is separated from the main body of ink within the nozzle chamber 1810 when the pressure is reduced. The separated ink continues to the paper. Preferably, the shutter is kept open so that the ink channel may refill during the next high pressure cycle. Afterwards it is rapidly shut so that the nozzle chamber remains full during subsequent low cycles of the oscillating ink pressure. The nozzle chamber is then ready for subsequent refiring on demand. The inkjet nozzle chamber 1810 can be constructed as part of an array of inkjet nozzles through MEMS depositing of the various layers utilizing the required masks, starting with a CMOS layer 1812 on top of which the nitride layer 1813 is deposited having the requisite slots. A sacrificial glass layer can then be deposited followed by a bottom portion of the PTFE layer 1822, followed by the copper layer 1823 with the lower layers having suitable vias for interconnecting with the copper layer. Next, an upper PTFE layer is deposited so as to encase to the copper layer 1823 within the PTFE layer 1822. A further sacrificial glass layer is then deposited and etched, before a nitride layer is deposited forming side walls 1840 and nozzle plate 1841. The nozzle plate 1841 is etched to have suitable nozzle hole 1842 and sacrificial etching nozzles 1843 with the plate also being etched to form a rim around the nozzle hole 1842. Subsequently, the sacrificial glass layers can be etched away, thereby releasing the structure of the actuator of the PTFE and copper layers. Additionally, the wafer can be through etched utilizing a high density low pressure plasma etching process such as that available from Surface Technology Systems. As noted previously many nozzles can be formed on a single wafer with the nozzles grouped into their desired width heads and the wafer diced in accordance with requirements. The diced printheads can then be interconnected to a printhead ink supply reservoir on the back portion thereof, for operation, producing a drop on demand ink jet printer. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 1811, complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer at this step are shown in 2. Etch the oxide layers down to silicon using Mask 1. This mask defines the lower fixed grill 1850. This step is shown in 3. Deposit 3 microns of sacrificial material 1851 (e.g. aluminum or photosensitive polyimide) 4. Planarize the sacrificial layer to a thickness of 0.5 micron over glass. This step is shown in 5. Etch the sacrificial layer using Mask 2. This mask defines the nozzle chamber walls and the actuator anchor points. This step is shown in 6. Deposit 1 micron of PTFE 1852. 7. Etch the PTFE and oxide down to second level metal using Mask 3. This mask defines the heater vias. This step is shown in 8. Deposit 1 micron of a conductor with a low Young's modulus 1853, for example aluminum or gold. 9. Pattern the conductor using Mask 4. This step is shown in 10. Deposit 1 micron of PTFE 1855. 11. Etch the PTFE down to the sacrificial layer using Mask 5. This mask defines the actuator and shutter This step is shown in 12. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 13. Deposit 6 microns of sacrificial material 1856. 14. Etch the sacrificial material using Mask 6. This mask defines the nozzle chamber wall 1840. This step is shown in 15. Deposit 3 microns of PECVD glass 1857. 16. Etch to a depth of (approx.) 1 micron using Mask 7. This mask defines the nozzle rim 1844. This step is shown in 17. Etch down to the sacrificial layer using Mask 6. This mask defines the roof 1841 of the nozzle chamber, the nozzle 1842, and the sacrificial etch access holes 1843. This step is shown in 18. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 7. This mask defines the ink inlets 1819 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in 19. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in 20. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. 21. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 22. Hydrophobize the front surface of the printheads. 23. Fill the completed printheads with ink 1860 and test them. A filled nozzle is shown in IJ19 A preferred embodiment utilises an ink reservoir with oscillating ink pressure and a shutter activated by a thermal actuator to eject drops of ink. Turning now to In Each of the ink nozzle arrangements of Referring now to A current is passed through the two arms 1924, 1925 via bonding pads 1932, 1933. The arm 1924 includes the inner core 1940 which is an inner resistive element, preferably comprising polysilicon or the like which heats up upon a current being passed through it The thermal jacket 1941 is provided to isolate the inner core 1940 from the ink chamber 1911 in which the arms 1924, 1925 are immersed. It should be noted that the arm 1924 contains a thermal jacket 1941 whereas the arm 1925 does not include a thermal jacket Hence, the arm 1925 will be generally cooler than the arm 1924 and undergoes a different rate of thermal expansion. The two arms act together to form a thermal actuator. The thermocouple comprising arms 1924, 1925 results in movement of the shutter 1930 generally in the direction 1934 upon a current being passed through the two arms. Importantly, the arm 1925 includes a thinned portion 1936 (in Returning now to An example timing diagram of operation of each ink nozzle arrangement will now be described. In Also shown in At the start of the drop formation phase 1971 when the pressure 1970 within the ink chamber is going from a negative pressure to a positive pressure, the actuator 1950 is actuated at 1959 to an open state. Subsequently, the shutter 1930 is also actuated at 1960 so that it also moves from a closed to an open position. Next, the actuator 1950 is deactivated at 1961 thereby locking the shutter 1930 in an open position with the head 1963 ( As the ink chamber and ink nozzle are in a positive pressure state at this time, the ink meniscus will be expanding out of the ink nozzle. Subsequently, the drop separation phase 1972 is entered wherein the chamber undergoes a negative pressure causing a portion of the ink flowing out of the ink nozzle back into the chamber. This rapid flow causes ink bubble separation from the main body of ink. The ink bubble or jet then passes to the print media while the surface meniscus of the ink collapses back into the ink nozzle. Subsequently, the pressure cycle enters the drop refill stage 1973 with the shutter 1930 still open with a positive pressure cycle experienced. This causes rapid refilling of the ink chamber. At the end of the drop re-filling stage, the actuator 1950 is opened at 1997 causing the now cold shutter 1930 to spring back to a closed position. Subsequently, the actuator 1950 is closed at 1964 locking the shutter 1930 in the closed position, thereby completing one cycle of printing. The closed shutter 1930 allows a drop settling stage 1974 to be entered which allows for the dissipation of any resultant ringing or transient in the ink meniscus position while the shutter 1930 is closed. At the end of the drop settling stage, the state has returned to the start of the drop formation stage 1971 and another drop can be ejected from the ink nozzle. Of course, a number of refinements of operation are possible. In a first refinement, the pressure wave oscillation which is shown to be a constant oscillation in magnitude and frequency can be altered in both respects. The size and period of each cycle can be scaled in accordance with such pre-calculated factors such as the number of nozzles ejecting ink and the tuned pressure requirements for nozzle refill with different inks. Further, the clock periods of operation can be scaled to take into account differing effects such as actuation speeds etc. Turning now to The ink jet nozzles are constructed on a buried boron-doped layer 1981 of a silicon wafer 1982 which includes fabricated nozzle rims, e.g. 1983 which form part of the layer 1981 and limit any hydrophilic spreading of the meniscus on the bottom end of the layer 1981. The nozzle rim, e.g. 1983 can be dispensed with when the bottom surface of layer 1981 is suitably treated with a hydrophobizing process. On top of the wafer 1982 is constructed a CMOS layer 1985 which contains all the relevant circuitry required for driving of the two nozzles. This CMOS layer is finished with a silicon dioxide layer 1986. Both the CMOS layer 1985 and the silicon dioxide 1986 include triangular apertures 1987 and 1988 allowing for fluid communication with the nozzle ports, e.g. 1984. On top of the SiO2 layer 1986 are constructed the various shutter layers 1990 to 1992. A first shutter layer 1990 is constructed from a first layer of polysilicon and comprises the shutter and actuator mechanisms. A second shutter layer 1991 can be constructed from a polymer, for example, polyamide and acts as a thermal insulator on one arm of each of the thermocouple devices. A final covering cage layer 1992 is constructed from a second layer of polysilicon. The construction of the nozzles 1980 relies upon standard semi-conductor fabrication processes and MEMS process known to those skilled in the art. One form of construction of nozzle arrangement 1980 would be to utilize a silicon wafer containing a boron doped epitaxial layer which forms the final layer 1981. The silicon wafer layer 1982 is formed naturally above the boron doped epitaxial 1981. On top of this layer is formed the layer 1985 with the relevant CMOS circuitry etc. being constructed in this layer. The apertures 1987, 1988 can be formed within the layers by means of plasma etching utilizing an appropriate mask. Subsequently, these layers can be passivated by means of a nitride covering and then filled with a sacrificial material such as glass which will be subsequently etched. A sacrificial material with an appropriate mask can also be utilized as a base for the moveable portions of the layer 1990 which are again deposited utilizing appropriate masks. Similar procedures can be carried out for the layers 1991, 1992. Next, the wafer can be thinned by means of back etching of the wafer to the boron doped epitaxial layer 1991 which is utilized as an etchant stop. Subsequently, the nozzle rims and nozzle apertures can be formed and the internal portions of the nozzle chamber and other layers can be sacrificially etched away releasing the shutter structure. Subsequently, the wafer can be diced into appropriate print heads attached to an ink chamber wafer and tested for operational yield. Of course, many other materials can be utilized to form the construction of each layer. For example, the shutter and actuators could be constructed from tantalum or a number of other substances known to those skilled in the art of construction of MEMS devices. It will be evident to the person skilled in the art, that large arrays of ink jet nozzle pairs can be constructed on a single wafer and ink jet print heads can be attached to a corresponding ink chamber for driving of ink through the print head, on demand, to the required print media. Further, normal aspects of (MEMS) construction such as the utilization of dimples to reduce the opportunity for stiction, while not specifically disclosed in the current embodiment could be used as means to improve yield and operation of the shutter device as constructed in accordance with a preferred embodiment. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 1975 deposit 3 microns of epitaxial silicon heavily doped with boron 1981. 2. Deposit 10 microns of n/n+ epitaxial silicon 1982. Note that the epitaxial layer is substantially thicker than required for CMOS. This is because the nozzle chambers are crystallographically etched from this layer. This step is shown in 3. Plasma etch the epitaxial silicon 1982 with approximately 90 degree sidewalls using MEMS Mask 1. This mask defines the nozzle cavity 1922. The etch is timed for a depth approximately equal to the epitaxial silicon 1982 (10 microns), to reach the boron doped silicon buried layer 1981. This step is shown in 4. Deposit 10 microns of low stress sacrificial oxide 1976. Planarize down to silicon 1982 using CMP. The sacrificial material 1976 temporarily fills the nozzle cavity. This step is shown in 5. Begin fabrication of the drive transistors, data distribution, and timing circuits using a CMOS process. The MEMS processes which form the mechanical components of the inkjet are interleaved with the CMOS device fabrication steps. The example given here is of a 1 micron, 2 poly, 1 metal retrograde P-well process. The mechanical components are formed from the CMOS polysilicon layers 1985. For clarity, the CMOS active components are omitted. 6. Grow the field oxide using standard LOCOS techniques to a thickness of 0.5 microns. As well as the isolation between transistors, the field oxide is used as a MEMS sacrificial layer, so inkjet mechanical details are incorporated in the active area mask. The MEMS features of this step are shown in 7. Perform the PMOS field threshold implant. The MEMS fabrication has no effect on this step except in calculation of the total thermal budget 8. Perform the retrograde P-well and NMOS threshold adjust implants. The MEMS fabrication has no effect on this step except in calculation of the total thermal budget. 9. Perform the PMOS N-tub deep phosphorus punchtrrough control implant and shallow boron implant The MEMS fabrication has no effect on this step except in calculation of the total thermal budget. 10. Deposit and etch the first polysilicon layer 1994. As well as gates and local connections, this layer 1994 includes the lower layer of MEMS components. This includes the shutter, the shutter actuator, and the catch actuator. It is preferable that this layer 1994 be thicker than the normal CMOS thickness. A polysilicon thickness of 1 micron can be used. The MEMS features of this step are shown in 11. Perform the NMOS lightly doped drain (LDD) implant This process is unaltered by the inclusion of MEMS in the process flow. 12. Perform the oxide deposition and RIE etch for polysilicon gate sidewall spacers. This process is unaltered by the inclusion of MEMS in the process flow. 13. Perform the NMOS source/drain implant. The extended high temperature anneal time to reduce stress in the two polysilicon layers must be taken into account in the thermal budget for diffusion of this implant. Otherwise, there is no effect from the MEMS portion of the chip. 14. Perform the PMOS source/drain implant. As with the NMOS source/drain implant, the only effect from the MEMS portion of the chip is on thermal budget for diffusion of this implant. 15. Deposit 1.3 micron of glass 1977 as the first interlevel dielectric and etch using the CMOS contacts mask. The CMOS mask for this level also contains the pattern for the MEMS inter-poly sacrificial oxide. The MEMS features of this step are shown in 16. Deposit and etch the second polysilicon layer 1978. As well as CMOS local connections, this layer 1978 includes the upper layer of MEMS components. This includes the grill and the catch second layer (which exists to ensure that the catch does not ‘slip off’ the shutter. A polysilicon thickness of 1 micron can be used. The MEMS features of this step are shown in 17. Deposit 1 micron of glass 1979 as the second interlevel dielectric and etch using the CMOS via 1 mask. The CMOS mask for this level also contains the pattern for the MEMS actuator contacts. 18. Deposit and etch the metal layer. None of the metal appears in the MEMS area, so this step is unaffected by the MEMS process additions. However, all required annealing of the polysilicon should be completed before this step. The MEMS features of this step are shown in 19. Deposit 0.5 microns of silicon nitride (Si3N4) 1993 and etch using MEMS Mask 2. This mask defines the region of sacrificial oxide etch performed in step 24. The silicon nitride aperture is substantially undersized, as the sacrificial oxide etch is isotropic. The CMOS devices must be located sufficiently far from the MEMS devices that they are not affected by the sacrificial oxide etch The MEMS features of this step are shown in 20. Mount the wafer on a glass blank 1995 and back-etch the wafer 1981 using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. The MEMS features of this step are shown in 21. Plasma back-etch the boron doped silicon layer 1981 to a depth of 1 micron using MEMS Mask 3. This mask defines the nozzle rim 1983. The MEMS features of this step are shown in 22. Plasma back-etch through the boron doped layer 1981 using MEMS Mask 4. This mask defines the nozzle 1984, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank The MEMS features of this step are shown in 23. Detach the chips from the glass blank 1995. Strip the adhesive. This step is shown in 24. Etch the sacrificial oxide 1976 using vapor phase etching (VPE) using an anhydrous HF/methanol vapor mixture. The use of a dry etch avoids problems with stiction. This step is shown in 25. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. 26. Connect the print heads to their interconnect systems. 27. Hydrophobize the front surface of the print heads. 28. Fill the completed print heads with ink 1996 and test them. A filled nozzle is shown in IJ20 In a preferred embodiment, an ink jet printhead is constructed from an array of ink nozzle chambers which utilize a thermal actuator for the ejection of ink having a shape reminiscent of the calyx arrangement of a flower. The thermal actuator is activated so as to close the flower arrangement and thereby cause the ejection of ink from a nozzle chamber formed in the space above the calyx arrangement The calyx arrangement has particular advantages in allowing for rapid refill of the nozzle chamber in addition to efficient operation of the thermal actuator. Turning to An important advantageous feature of a preferred embodiment is that PTFE is normally hydrophobic. In a preferred embodiment the bottom surface of petals 2013 comprises untreated PTFE and is therefore hydrophobic. This results in an air bubble 2020 forming under the surface of the petals. The air bubble contracts on upward movement of petals 2013 as illustrated in The top of the petals is treated so as to reduce its hydrophobic nature. This can take many forms, including plasma damaging in an ammonia atmosphere. The top of the petals 2013 is treated so as to generally make it hydrophilic and thereby attract ink into nozzle chamber 2016. Returning now to The wafer 2025 can comprise a standard silicon wafer on top of which is constructed data drive circuitry which can be constructed in the usual manner such as two level metal CMOS with portions 2026 of one level of metal (aluminium) being used for providing interconnection with the copper circuitry portions 2027. The arrangement 2010 of Turning now to The arrangement 2010 can be constructed on a silicon wafer using micro-electro-mechanical systems techniques. The PTFE layer 2030 can be constructed on a sacrificial material base such as glass, wherein a via for stem 2033 of layer 2030 is provided. The layer 2032 is constructed on a second sacrificial etchant material base so as to form the nitride layer 2032. The sacrificial material is then etched away using a suitable etchant which does not attack the other material layers so as to release the internal calyx structure. To this end, the nozzle plate 2032 includes the aforementioned etchant holes e.g. 2023 so as to speed up the etching process, in addition to the nozzle 2017 and the nozzle rim 2034. The nozzles 2010 can be formed on a wafer of printheads as required. Further, the printheads can include supply means either in the form of a “through the wafer” ink supply means which uses high density low pressure plasma etching such as that available from Surface Technology Systems or via means of side ink channels attached to the side of the printhead. Further, areas can be provided for the interconnection of circuitry to the wafer in the normal fashion as is normally utilized with MEMS processes. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 2025, Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 2026. This step is shown in 2. Etch through the silicon dioxide layers of the CMOS process down to silicon using mask 1. This mask defines the ink inlet channels and the heater contact vias 2050. This step is shown in 3. Deposit 1 micron of low stress nitride 2029. This acts as a barrier to prevent ink diffusion through the silicon dioxide of the chip surface. This step is shown in 4. Deposit 3 micron of sacrificial material 2051 (e.g. photosensitive polyimide) 5. Etch the sacrificial layer using mask 2. This mask defines the actuator anchor point This step is shown in 6. Deposit 0.5 micron of PTFE 2052. 7. Etch the PTFE, nitride, and oxide down to second level metal using mask 3. This mask defines the heater vias. This step is shown in 8. Deposit 0.5 micron of heater material 2031 with a low Young's modulus, for example aluminum or gold. 9. Pattern the heater using mask 4. This step is shown in 10. Wafer probe. All electrical connections are complete at this point, and the chips are not yet separated. 11. Deposit 1.5 microns of PTFE 2053. 12. Etch the PTFE down to the sacrificial layer using mask 5. This mask defines the actuator petals. This step is shown in 13. Plasma process the PTFE to make the top surface hydrophilic. 14. Deposit 6 microns of sacrificial material 2054. 15. Etch the sacrificial material to a depth of 5 microns using mask 6. This mask defines the suspended walls 2021 of the nozzle chamber. 16. Etch the sacrificial material down to nitride using mask 7. This mask defines the nozzle plate supporting posts 2024 and the walls surrounding each ink color (not shown). This step is shown in 17. Deposit 3 microns of PECVD glass 2055. This step is shown in 18. Etch to a depth of 1 micron using mask 8. This mask defines the nozzle rim 2034. This step is shown in 19. Etch down to the sacrificial layer using mask 9. This mask defines the nozzle 2017 and the sacrificial etch access holes 2023. This step is shown in 20. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using mask 10. This mask defines the ink inlets 2056 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in 21. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch This step is shown in 22. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. 23. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 24. Hydrophobize the front surface of the printheads. 25. Fill the completed printheads with ink 2057 and test them. A filled nozzle is shown in IJ21 Turning initially to Turning now to Each nozzle arrangement 2112 includes an ink ejection port 2113 for the output of ink and a nozzle chamber 2114 which is normally filled with ink. Further, each nozzle arrangement 2112 is provided with a shutter 2110 which is designed to open and close the nozzle chamber 2114 on demand. The shutter 2110 is actuated by a coiled thermal actuator 2115. The coiled actuator 2115 is constructed from laminated conductors of either differing resistivities, different cross-sectional areas, different indices of thermal expansion, different thermal conductivities to the ink, different length, or some combination thereof. A coiled radius of the actuator 2115 changes when a current is passed through the conductors, as one side of the coiled actuator 2115 expands differently to the other. One method, as illustrated in The thermal actuator 2115 controls the position of the shutter 2110 so that it can cover none, all or part of the nozzle chamber 2114. If the shutter 2110 does not cover any of the nozzle chamber 2114 then the oscillating ink pressure will be transmitted to the nozzle chamber 2114 and the ink will be ejected out of the ejection port 2113. When the shutter 2110 covers the ink chamber 2114, then the oscillating ink pressure of the chamber is significantly attenuated at the ejection port 2113. The ink pressure within the chamber 2114 will not be entirely stopped, due to leakage around the shutter 2110 when in a closed position and fixing of the shutter 2110 under varying pressures. The shutter 2110 may also be driven to be partly across the nozzle chamber 2114, resulting in a partial attenuation of the ink pressure variation. This can be used to vary the volume of the ejected drop. This can be utilized to implement a degree of continuation tone operation of the printing mechanism 2101 ( The operation of the ink jet nozzle arrangement 2112 will now be explained in further detail. Referring to The operation of the printing mechanism 2101 utilizes four phases being an ink ejection phase 2171, an ink separation phase 2172, an ink refill phase 2173 and an idle phase 2174. Referring now to At the start of the ejection phase 2171 the actuator coil is activated and the shutter 2110 moves away from its position over the chamber 2114 as illustrated in Subsequently, the ink chamber 2114 enters the refill phase 2173 of The cyclic operation as illustrated in Further, the amplitude of the driving signal to the actuator 2104 can be altered in response to the viscosity of the ink which will typically be effected by such factors as temperature and the number of drops which are to be ejected in the current cycle. Construction and Fabrication Each nozzle arrangement 2112 further includes drive circuitry which activates the actuator coil when the shutter 2110 is to be opened. The nozzle chamber 2114 should be carefully dimensioned and a radius of the ejection port 2113 carefully selected to control the drop velocity and drop size. Further, the nozzle chamber 2114 of Preferably, the shutter 2110 is of a disk form which covers the nozzle chamber 2114. The disk preferably has a honeycomb-like structure to maximize strength while minimizing its inertial mass. Preferably, all surfaces are coated with a passivation layer so as to reduce the possibility of corrosion from the ink flow. A suitable passivation layer can include silicon nitride (Si3N4), diamond like carbon (DLC), or any other chemically inert, highly impermeable layer. The passivation layer is especially important for device lifetime, as the active device will be immersed in ink. Fabrication Sequence 1) Start with a single crystal silicon wafer 2140, which has a buried epitaxial layer 2141 of silicon which is heavily doped with boron. The boron should be doped to preferably 1020 atoms per cm3 of boron or more, and be approximately 2 micron thick. The lightly doped silicon epitaxial layer on top of the boron doped layer should be approximately 8 micron thick, and be doped in a manner suitable for the active semiconductor device technology chosen. This is hereinafter called the “Sopij” wafer. The wafer diameter should be the same as the ink channel wafer. 2) Fabricate the drive transistors and data distribution circuitry according to the process chosen in the CMOS layer 2142, up until the oxide extends over second level metal. 3) Planarize the wafer using Chemical Mechanical Planarization (CMP). 4) Plasma etch the nozzle chamber, stopping at the boron doped epitaxial silicon layer. This etch will be through around 8 micron of silicon. The etch should be highly anisotropic, with near vertical sidewalls. The etch stop determination can be the detection of boron in the exhaust gases. This step also etches the edge of printhead chips down to the boron layer 2141, for later separation. 5) Conformally deposit 0.2 microns of high density Si3N4 2143. This forms a corrosion barrier, so should be free of pinholes and be impermeable to OH ions. 6) Deposit a thick sacrificial layer. This layer should entirely fill the nozzle chambers 2114, and coat the entire wafer to an added thickness of 2 microns. The sacrificial layer may be SiO2, for example, spin or glass (SOG). 7) Mask and etch the sacrificial layer using the coil post mask. 8) Deposit 0.2 micron of silicon nitride (Si3N4). 9) Mask and etch the Si3N4 layer using the coil electric contacts mask, a first layer of PTFE layer 2144 using the coil mask. 10) Deposit 4 micron of nichrome alloy (NiCr). 11) Deposit the copper conductive layer 2145 and etch using the conductive layer mask. 12) Deposit a second layer of PTFE using the coil mask. 13) Deposit 0.2 micron of silicon nitride (Si3N4) (not shown). 14) Mask and etch the Si3N4, layer using the spring passivation and bond pad mask 15) Permanently bond the wafer onto a pre-fabricated ink channel wafer. The active side of the Sopij wafer faces the ink channel wafer. 16) Etch the Sopij wafer to entirely remove the backside silicon to the level of the boron doped epitaxial layer. This etch can be a batch wet etch in ethylene-diamine pyrocatechol (EPD). 17) Mask the ejection ports 2113 from the underside of the Sopij wafer. This mask also includes the chip edges. 18) Etch through the boron doped silicon layer 2141. This etch should also etch fairly deeply into the sacrificial material in the nozzle chambers 2114 to reduce time required to remove the sacrificial layer. 19) Completely etch the sacrificial material. If this material is SiO2, then an HF etch can be used. Access of the HF to the sacrificial layer material is through the ejection port 2113, and simultaneously through an ink channel in the chip. 20) Separate the chips from the backing plate. The two wafers have already been etched through, so the printheads do not need to be diced. 21) TAB bond the good chips. 22) Perform final testing on the TAB bonded printheads. One alternative form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double-sided polished wafer 2150 deposit 3 microns of epitaxial silicon 2141 heavily doped with boron. 2. Deposit 10 microns of epitaxial silicon 2140, either p-type or n-type, depending upon the CMOS process used. 3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 2142. The wafer is passivated with 0.1 microns of silicon nitride 2143. This step is shown in 4. Etch the CMOS oxide layers down to silicon using Mask 1. This mask defines the nozzle chamber 2114 below the shutter 2110, and the edges of the printhead chips. 5. Plasma etch the silicon down to the boron doped buried layer 2141, using oxide from step 4 as a mask. This step is shown in 6. Deposit 6 microns of sacrificial material 2151 (e.g. aluminum or photosensitive polyimide) 7. Planarize the sacrificial layer 2151 to a thickness of 1 micron over nitride 2143. This step is shown in FIG. 421. 8. Etch the sacrificial layer 2151 using Mask 2. This mask defines the actuator anchor point 2152. This step is shown in 9. Deposit 1 micron of PTFE 2144. 10. Etch the PTFE, nitride, and oxide down to second level metal using Mask 3. This mask defines the heater vias. This step is shown in 11. Deposit 1 micron of a conductor 2145 with a low Young's modulus, for example aluminum or gold. 12. Pattern the conductor using Mask 4. This step is shown in 13. Deposit 1 micron of PTFE. 14. Etch the PTFE down to the sacrificial layer using Mask 5. This mask defines the actuator 2115 and shutter 2110 ( 15. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 16. Mount the wafer on a glass blank 2153 and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer 2141. This step is shown in 17. Plasma back-etch the boron doped silicon layer 2141 to a depth of (approx.) 1 micron using Mask 6. This mask defines the nozzle rim 2154. This step is shown in 18. Plasma back-etch through the boron doped layer using Mask 7. This mask defines the nozzle 2113, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank 2153. This step is shown in 19. Detach the chips from the glass blank 2153 and etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch This step is shown in 20. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. 21. Connect the printheads to their interconnect systems. 22. Hydrophobize the front surface of the printheads. 23. Fill the completed printheads with ink 2155 and test them. A filled nozzle is shown in IJ22 In a preferred embodiment, there is a provided an ink jet printhead which includes a series of nozzle arrangements, each nozzle arrangement including an actuator device comprising a plurality of actuators which actuate a series of paddles that operate in an iris type motion so as to cause the ejection of ink from a nozzle chamber. Turning initially to Each nozzle vane 2214 is actuated by means of a thermal actuator 2215 positioned at its base. Each thermal actuator 2115 has two arms namely, an expanding, flexible arm 2225 and a rigid arm 2226. Each actuator is fixed at one end 2227 and is displaceable at an opposed end 2228. Each expanding arm 2225 can be constructed from a polytetrafluoroethylene (PTFE) layer 2229, inside of which is constructed a serpentine copper heater 2216. The rigid arm 2226 of the thermal actuator 2215 comprises return trays of the copper heater 2216 and the vane 2214. The result of the heating of the expandable arms 2225 of the thermal actuators 2215 is that the outer PTFE layer 2229 of each actuator 2215 is caused to bend around thereby causing the vanes 2214 to push ink towards the centre of the nozzle chamber 2212. The serpentine trays of the copper layer 2216 concertina in response to the high thermal expansion of the PTFE layer 2229. The other vanes 2218-2220 are operated simultaneously. The four vanes therefore cause a general compression of the ink within the nozzle chamber 2212 resulting in a subsequent ejection of ink from the ink ejection port 2211. A roof 2222 of the nozzle arrangement 2210 is formed from a nitride layer and is supported by posts 2223. The roof 2222 includes a series of holes 2224 which are provided in order to facilitate rapid etching of sacrificial materials within lower layers during construction. The holes 2224 are provided of a small diameter such that surface tension effects are sufficient to stop any ink being ejected from the nitride holes 2224 as opposed to the ink ejection port 2211 upon activation of the iris vanes 2214. The arrangement of On top of the nitride layer 2232 is constructed the aluminum layer 2233 which includes various heater circuits in addition to vias to the lower CMOS layer. Next a PTFE layer 2234 is provided with the PTFE layer 2234 comprising layers which encase a lower copper layer 2233. Next, a first nitride layer 2236 is constructed for the iris vanes 2214, 2218-2220 of The various layers 2233, 2234, 2236 and 2237 can be constructed utilizing intermediate sacrificial layers which are, as standard with MEMS processes, subsequently etched away so as to release the functional device. Suitable sacrificial materials include glass. When necessary, such as in the construction of nitride layer 2237, various other semi-conductor processes such as dual damascene processing can be utilized. One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer 2230, complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 2231. The wafer is passivated with 0.1 microns of silicon nitride 2232. Relevant features of the wafer at this step are shown in 2. Deposit 1 micron of sacrificial material 2241 (e.g. aluminum or photosensitive polyimide) 3. Etch the sacrificial layer using Mask 1. This mask defines the nozzle chamber posts 2223 and the actuator anchor point This step is shown in 4. Deposit 1 micron of PTFE 2242. 5. Etch the PTFE, nitride, and oxide down to second level metal using Mask 2. This mask defines the heater vias. This step is shown in 6. Deposit 1 micron of a conductor 2216 with a low Young's modulus, for example aluminum or gold. 7. Pattern the conductor using Mask 3. This step is shown in 8. Deposit 1 micron of PTFE. 9. Etch the PTFE down to the sacrificial layer using Mask 4. This mask defines the actuators 2215. This step is shown in 10. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated. 11. Deposit 6 microns of sacrificial material 2243. 12. Etch the sacrificial material using Mask 5. This mask defines the iris paddle vanes 2214, 2218-2220 and the nozzle chamber posts 2223. This step is shown in 13. Deposit 3 microns of PECVD glass and planarize down to the sacrificial layer using CMP. 14. Deposit 0.5 micron of sacrificial material. 15. Etch the sacrificial material down to glass using Mask 6. This mask defines the nozzle chamber posts 2223. This step is shown in 16. Deposit 3 microns of PECVD glass 2244. 17. Etch to a depth of (approx.) 1 micron using Mask 7. This mask defines a nozzle rim. This step is shown in 18. Etch down to the sacrificial layer using Mask 8. This mask defines the roof 2222 of the nozzle chamber 2212, the port 2211, and the sacrificial etch access holes 2224. This step is shown in 19. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 9. This mask defines the ink inlets 2245 which are etched through the wafer. When the silicon layer is etched, change the etch chemistry to etch the glass and nitride using the silicon as a mask. The wafer is also diced by this etch This step is shown in 20. Etch the sacrificial material. The nozzle chambers 2212 are cleared, the actuators 2215 freed, and the chips are separated by this etch. This step is shown in 21. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. 22. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper. 23. Hydrophobize the front surface of the printheads. 24. Fill the completed printheads with ink 2246 and test them. A filled nozzle is shown in IJ23 In a preferred embodiment, ink is ejected from a nozzle arrangement by bending of a thermal actuator so as to eject t ink. Turning now to The copper resistive element 2308 is constructed in a serpentine manner to provide very little tensile strength along the length of the thermal actuator panel 2302. The copper resistive element 2308 is embedded in a polytetrafluoroethylene (PTFE) layer 2312. The PTFE layer 2312 has a very high coefficient of thermal expansion (approximately 770×10−6). This layer undergoes rapid expansion when heated by the copper heater 2308. The copper heater 2308 is positioned closer to a top surface of the PTFE layer 2312, thereby heating an upper layer of the PTFE layer 2312 faster than the bottom layer, resulting in a bending down of the thermal actuator 2302 towards the ejection port 2304. The operation of the nozzle arrangement 2301 is as follows: 1) When data signals distributed on the printhead indicate that the nozzle arrangement is to eject a drop of ink, a drive transistor for the nozzle arrangement is turned on. This energizes the leads 2306, 2307, and the heater 2308 in the actuator 2302 of the nozzle arrangement. The heater 2308 is energized for approximately 3 microseconds, with the actual duration depending upon the design chosen for the nozzle arrangement. 2) The heater heats the PTFE layer 2312, with the top layer of the PTFE layer 2312 being heated more rapidly than the bottom layer. This causes the actuator to bend generally towards the ejection port 2304, in to the nozzle chamber 2303, as illustrated in 3) When the heater current is turned off, the actuator 2302 begins to return to its quiescent position. The return of the actuator 2302 ‘sucks’ some of the ink back into the nozzle chamber 2303, causing an ink ligament connecting the ink drop to the ink in the chamber 2303 to thin. The forward velocity of the drop and backward velocity of the ink in the chamber are resolved by the ink drop breaking off from the ink in the chamber 2303. The ink drop then continues towards the recording medium. 4) The actuator 2302 remains at the quiescent position until the next drop ejection cycle. Construction In order to construct a series of the nozzle arrangement 2301 the following major parts need to be constructed: 1) Drive circuitry to drive the nozzle arrangement 2301. 2) The ejection port 2304. The radius of the ejection port 2304 is an important determinant of drop velocity and drop size. 3) The actuator 2302 is constructed of a heater layer embedded in the PTFE layer 2312. The actuator 2302 is fixed at one side of the ink chamber 2303, and the other end is suspended ‘over’ the ejection port 2304. Approximately half of the actuator 2302 contains the copper element 2308. A heater section of the element 2308 is proximate the fixed end of the actuator 2302. 4) The nozzle chamber 2303. The nozzle chamber 2303 is slightly wider than the actuator 2302. The gap between the actuator 2302 and the nozzle chamber 2303 is determined by the fluid dynamics of the ink ejection and refill process. If the gap is too large, much of the actuator force will be wasted on pushing ink around the edges of the actuator. If the gap is too small, the ink refill time will be too long. Also, if the gap is too small, the crystallographic etch of the nozzle chamber will take too long to complete. A 2 micron gap will usually be sufficient. The nozzle chamber is also deep enough so that air ingested through the ejection port 2304 when the actuator returns to its quiescent state does not extend to the actuator. If it does, the ingested bubble may form a cylindrical surface instead of a hemispherical surface. If this happens, the chamber 2303 will not refill properly. A depth of approximately 20 micron is suitable. 5) Nozzle chamber ledges 2313. As the actuator 2302 moves approximately 10 microns, and a crystallographic etch angle of chamber surface 2314 is 54.74 degrees, a gap of around 7 micron is required between the edge of the paddle 2302 and the outermost edge of the nozzle chamber 2303. The walls of the nozzle chamber 2303 must also clear the ejection port 2304. This requires that the nozzle chamber 2303 be approximately 52 micron wide, whereas the actuator 2302 is only 30 micron wide. Were there to be an 11 micron gap around the actuator 2302, too much ink would flow around to the sides of the actuator 2302 when the actuator 2302 is energized. To prevent this, the nozzle chamber 2303 is undercut 9 micron into the silicon surrounding the paddle, leaving a 9 micron wide ledge 2313 to prevent ink flow around the actuator 2302. Basic Fabrication Sequence Two wafers are required: a wafer upon which the active circuitry and nozzles are fabricated (the print head wafer) and a further wafer in which the ink channels are fabricated. This is the ink channel wafer. One form of construction of printhead wafer will now be discussed with reference to 1) Starting with a single crystal silicon wafer, which has a buried epitaxial layer 2316 of silicon which is heavily doped with boron. The boron should be doped to preferably 1020 atoms per cm3 of boron or more, and be approximately 3 micron thick The lightly doped silicon epitaxial layer 2315 on top of the boron doped layer should be approximately 8 micron thick, and be doped in a manner suitable for the active semiconductor device technology chosen. This is the printhead wafer. The wafer diameter should preferably be the same as the ink channel wafer. 2) The drive transistors and data distribution circuitry layer 2317 is fabricated according to the process chosen, up until the oxide layer over second level metal. 3) Next, a silicon nitride passivation layer 2318 is deposited. 4) Next, the actuator 2302 ( 5) Etch through the PTFE, and all the way down to silicon in the region around the three sides of the paddle. The etched region should be etched on all previous lithographic steps, so that the etch to silicon does not require strong selectivity against PTFE. 6) Etch the wafers in an anisotropic wet etch, which stops on <111> crystallographic planes or on heavily boron doped silicon. The etch can be a batch wet etch in ethylenediamine pyrocatechol (EDP). The etch proceeds until the paddles are entirely undercut thereby forming the nozzle chamber 2303. The backside of the wafer need not be protected against this etch, as the wafer is to be subsequently thinned. Approximately 60 micron of silicon will be etched from the wafer backside during this process. 7) Permanently bond the printhead wafer onto a pre-fabricated ink channel wafer. The active side of the printhead wafer faces the ink channel wafer. The ink channel wafer is attached to a backing plate, as it has already been etched into separate ink channel chips. 8) Etch the printhead wafer to entirely remove the backside silicon to the level of the boron doped epitaxial layer 2316. This etch can be a batch wet etch in ethylenediamine pyrocatechol (EDP). 9) Mask an ejection port rim 2311 ( | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||